Terms to Know – KJ iTech Corp

	Terms
1	Basic Operations	4 Major Tasks Computer Does >	Receive Input, Store Information, Process Information & Gives Output

2	Store Information	Data Store in the form of numbers according to ASCII Values	Numerals have numbers
			Alphabets & Symbols have numbers
			Control Characters have numbers like Esc, del, space etc
			Image, Video, Graphic have tiny pixels, each pixel have color in terms of RGB (Red, Green, Blue) and these colors have numbers (from 0-255) according to their brightness level. Average of thus numbers then mapped to ASCII number & further mapped to character with that ASCII value.
			Sound is in wave form and that wave form mapped to ASCII values

3	American Standard Code for Information Interchange (ASCII)	Its Character encoding structure	In total, ASCII values ranging from 0 to 255, Each number is of 8 bit
			Exp: ESC=27, #=35, 1=49, A=65, a=97
			Control characters have ASCII values from 0 to 32 & 127
			A character, numeral refer to an integer number, some common used symbols between 33 to 126 & other symbols from 128 to 255 which are known as ASCII values

4	Process Information	Computers process information by set Algoritm	Algorithm	Series of Instructions executed internally by CPU while processing information or to perform a computation

5	Wires System	Inside Computer have Circuits and these circuits have many wires >	Single Wire passes electric signal and have Status either ON or OFF. This Represent a Bit
			Information execute one by one in cpu with fraction of seconds in the form of binary numbers > on – off electrical pulses
			2 Wires process 2 Bit of information in fraction of second, 32 Wires = 32 Bit, 64 Wires = process 64 Bit of information

6	Circuits	AND, OR, NOT, NAND, NOR, XOR circuits give output electrical signals according to their characteristics wrt input electrical signals	These circuits connects in combinations to perform calculations in computers	Like Adder circuit to use for addition, Send/receive circuit use for information exchange, Store circuit to use store information in memory

7	Central Processing Unit (CPU)	Many of these Circuits are put on small chip called Micro Processor	Micro Processor, have all the circuits to do different job and it only decide which circuit to use for different calculations

6	Binary Numbers	Binary Number means 0 or 1 > Means ON or OFF > Means True or False	Bits & Bytes >	o Bit = 0 or 1 (smallest unit)
				o 1Byte = 8 Bit
				o 1KB = 1024 Bytes
				o 1MB = 1024 KB
				o 1GB = 1024 MB

7	Pixel	A tiny dot or square on computer screen thru which light comes out is called pixel	When pixel is ON it emits white light and when pixel is OFF then its emit no light and seen black to us	In the RGB color spectrum, red, green, and blue are the primary colors. These colors are used to create pure white light when added together
			All these pixels jointly make up the computer screen
			Pixels have RGB (Red/Green/Blue) values & emits colourful light according to colored image which show up on computer screen

	Resolution	Total number of pixels in each dimension along the width & height of computer screen is called Screen Resolution	Image has size in Width & Height. Total pixels in width * total pixels in height is called Image Resolution
	View Port	The portion of screen which changes according to dynamic content like the view of webpage on website is called the view port of screen in Browser

8	Memory (RAM & ROM)	RAM	ROM	Hard Disk / Solid State Disk
		Ramdom Access Memory	Read Only Memory	Storage Memory
		Computer store data for running process, once the process over, data deleted	Data in ROM is just read only and cannot be write more here	Data can be read & write
		Used by CPU	Used by System & User when need	Used by System & User when need
		Data never remains for always on RAM	Data remains forever in ROM	Data remains forever
		Very Fast	Slow comparative to RAM	Slow than RAM but fast from ROM

9	Storage Device (HDD & SSD)	HDD	SSD
		Hard Disk Drive	Solid State Drive
		This drive has moving parts like read/write heads & Magnetic disk, data store on disk by electromagnetism (head does not touch the disk), Slower in nature	This drive has no moving part, also called flash drives, data store by passsing electrical signals, Fast in nature
		Data can add, delete and store forever on HDD	Data can add, delete and store forever on SSD

10	Operating System (OS)	DOS (Disk Operating System) >	Its text based Operating System > have commands to type in CLI to do job
		Command Line Interface Tools (CLI) for Windows >	Command Prompt, Power Shell (More advanced than CMD)	Shell is a program that acts as an interface between the user and the operating system. Taken in DOS commands to execute those.
		Command Line Interface Tools for MacOS, Linux >	Console/Terminal, Bash/Zsh (is Shell for Linux type of OS)	Both CMD & Console have different set of text commands to execute same action

	Graphical Interface of OS	Windows, Mac OS, Linux distribution is Ubuntu

11	Applications (APP)	Desktop Applications
		Mobile Applications
		Web Applications
		API’s (Application Programing Interface)
		Embedded Chip Programs

12	Software Architecture Designing	represents the design decisions related to software overall structure & behaviour.	This is about what resources and modules to use in the construction of Software
		2 Tier / 3 Tier / N Tier Architecture >	2 Tier Architeture
			Database Tier & Presentation Tier, Exp: MS Excel
			3 Tier Architeture	Most of the applications work on this architecture
			Database Tier, Business Tier & Presentation Tier
			N Tier Architeture
			If data comes from diff. servers then it is called N Tier Architecture

	Application UI Designing	Graphic designing, Web Page designing, Mobile App Screen designing & Desktop App UI designing

13	Application Desirable Features	Web App Desirable Features >	User friendly Admin Portal
			Customized design & theme
			Cross browser compatibility
			Flash Web Design >	Use Vector animation software which create animation to display on web page in less size and rendered easily
			E-Commerce Website >	ability for money transaction
			W3C Compliance >	word wide web consortium

		Mobile App Desirable Features >	Well-designed user interface (UI)
			Fast loading time
			Strong data protection
			Excellent user support	Inbuilt support for user general queries
			Built-in integrations	Like app should get data and share data with other apps in the system
			Good general navigation and accessibility

14	Application Development Process	Gathering Information/Requirments, Requirment Analysis, Planning, Designing, Development, Quality Analysis, Deployment, User Experience, Bug fixing, Regression, Maintenance
	Web Application Development	Exp: By ASP.Net (Web Form + Business Tier + Database Tier) / .Net MVC Framework (Autogenrated Presentation Tier + Business Tier + Database Tier) / .Net Core technology (for API Creation – Business Tier + Database Tier) using C# or Visual Basic Language > called Backend or API	Run on Web Server > Generate data to handle by HTML > Data from API can also handle by Technology “React” which handle HTML > called frontend	HTML Understand by Web Browser
	Mobile Application Development	Develop thru Android Studio, Xcode, React Native (for cross platform) frameworks by using languages Kotlin, Swift, Javascript respectively > called frontend	API structure for mobile app remains the same as for web application
	Application Programming Interface (API)	Is a way to communicate betweem diff. parts of computer program intended to simplify the implementation and maintenance of software	Types of Request: GET, POST, PUT/UPDATE, DELETE

15	Type of Developers	Graphic Designers >	Design Visual Elements of Screen
		Front End Developer >	Handles GUI >	Coding for visual front elements which are directly access by user
		Back End Developer >	Handles Core Coding > API	Coding for core computational, airthmetic & logical operations which are indirectly access by user
		Full Stack Developer >	Done tasks of front and back end devleoper
		QA Analyst / Engineer >	Done Testing of the application
		DevOps >	Handles Source Code, Its deployment & migrations

16	World wide web (WWW)	Is the inter-connected computers network	Is the information system where documents & other web resources identified by URL ( Uniform resource Locator) and are accessible over the internet
	Uniform Resource Locator (URL)	is the specific IP Address	mapped to alphabets	End Points: are the slug after domain name in url which access particular resource of API
	Query Params	Query parameters are parameters added to the end of a URL to provide extra information to a web server when making requests.	those are usually passed on after ?, Like www.website.com/contact?param1=value&param2=value	url: www.website.com, endpoint or slug: /contact, Params: ?param1=value&param2=value
	Payload	refers to the data that’s sent in a request to server or received in a response from server, essentially the body of the HTTP message containing the actual information being exchanged between a client and a Server	the payload might contain the user’s name, email, and password in JSON format: {“name”: “John Doe”, “email”: “john.doe@example.com”, “password”: “securePassword”}

17	Domain Name System (DNS)	Associates URL with particular IP Address	Then computer use DNS Server to look partiuclar IP address correspond to URL typed	Query first come to DNS Resolver from DNS Client (Computer or router), DNS Resolver act as middle man for co-ordination. It directs query to Root NameServer.
			DNS Servers are connected in distributted hirarchy like connected in groups for .com only / .org only / .net only. This is called Top Level Domain	Root Nameserver is an index of all servers and points the resolver towards the appropriate top-level domain (TLD) nameserver (like .com or .org)
			DNS Servers are connected to the internet	The resolver then contacts the TLD nameserver, which in turn directs it to the Authoritative nameserver responsible for the specific domain you requested (e.g., google.com’s nameserver).
				Finally, the resolver reaches the authoritative nameserver, which holds the domain’s DNS records. This nameserver checks its records (like A records for IPv4 addresses) and finds the corresponding IP address for the requested domain name, give it to DNS resolver
				DNS resolver gives that it to DNS client.

18	Internet	Is the medium to connect to inter-connected computers network which is called world wide web, uses internet protocol to link devices world wide
	Internet Protocol (IP)	(Set of rules which all parties agrees to follow in order while communicating) > IP Address >	IPv 4 > (It is 4 sets of Numerals, 3 diff. numerals in each set totaling 8 bits, Grand totalling 4 sets = 32 bits) (Max 3 digit in each set of 4)	32 Bit Number > 32 Binary Number used for complete set of IP Address alloted to computer / each device. Number in each set range from 0 to 255
		IP have Network ID + Host ID	Class A – spans the values 0.0.0.0 to 127.255.255.255. This class, which has 8 bits for the network and 24 bits for hosts, is designed for large networks.	4 Sets of digits represents Country. Region. SubNetwork. Host id of Device. Totally 4 Billion devices can connect to internet.
		Loop back address – 127.0.0.1 to ping from CLI tool to get repsonse to check if NIC card broken	Class B – It is intended for medium-sized to big networks. fall between 128.0.0.0 and 191.255.255.255. It also contains 16 bits for hosts and 16 bits for the network.	Public IP addresses are coordinated by IANA (The Internet Assigned Numbers Authority, who first allocates the different IP addresses to five RIRs(Regional Internet Registries). Organizations in need of IP addresses apply to these allocation centers who coordinate the allocation.
			Class C – We use it for the small local area networks (LANs). The network in this class is indented using three octets. And the IP address has a range of 192.0.0.0 to 223.255.255.255, 24 network bits, and 8 host bits.	Private vs Public IP Address: Public IP is provided by ISP which can find on Google by “What is my ip” and same is masked to Private IP Address provided by your router/computer while connected to internet which can see in system settings
			Class D – are reserved for multicast communication, allowing a single data packet to be sent to a group of recipients simultaneously. That means we don’t use Class D for standard networking functions.	Rest all are public ip address except this range for private IP: 10.0.0.0 – 10.255.255.255, 172.16.0.0 – 172.31.255.255, 192.168.0.0 – 192.168.255.255
			Class E – We use it for experimental or study-related reasons. This class of IP addresses covers the first octet values 240.0.0.0 to 255.255.255.255.
			IPv 6 > It is the latest version of IP	128 Bit Number used in this, this version comes as no. of connected devices on internet increased manifolds since inception of IPv4
	Subnet Mask	255.255.255.1	A subnet mask is a 32 bit number that distinguishes the network address and the host address within an IP address (the network portion of an IP address from the host portion, enabling network segmentation and routing).	A subnet is a smaller network within a network that requires a subnet mask. Subnetting is the process of dividing a network into two or more subnets. like in 255.255.255.1, 255.255.255 is the network address & .1 is the host address (device id) which goes upto 255.
	Default Gateway for LAN	192.168.1.1	This is the default gate way to communicate over network if destination gate is unknown to sent & receive packet
	Internet Service Provider (ISP)	Tier 1 Network, Tier 2, Tier 3 Network (In Desending order, these are the companies / suppliers of internet infrastructure at diff. levels worldwide)	Tier 1 are the biggest companies
	Dynamic Host Configuration Protocol (DHCP)	Is a network management protocol used on Internet Protocol networks whereby a DHCP server assigned IP address to each device on a Local Network	LAN IP’s allocated by DHCP upto value as specified in Subnet Mask
	Virtual Private Network (VPN)	is a secure connection that allows you to access the internet as if you were on a private network, masking your IP address and encrypting your data for enhanced privacy and security.	VPN operate at the system level encrypits the data, further encrypted data is then wrapped inside additional data packets, The data packets is transmitted through a protected tunnel (This shields both the content and metadata) to the VPN server, VPN server decrypted data, assigned a new virtual IP address, and forwarded to its intended destination. VPN repeats this process in reverse when sending back response to client	VPN hides: Location and IP address, Recent searches (hidden from ISP), Websites you’ve visited (hidden from ISP), Data you send and receive, Files you download.
				VPN Not Hide: Activity on sites you’re logged into [do not login at any site], Activity tracked by cookies [delete cookies], Device browser history [use private browser], Browser fingerprinting and ad-tracking data [its browser property – use not to track feature], The simple fact you’re using a VPN (VPN server IP Address you connected with)

19	Bandwidth	Maximum Number of Bits can be send / second
	Bit Rate	Number of Bits sent / second
	Latency	Time taken by a Bit to travel from source to destination and receive back first repsonse from server
	Bits Sending Medium	Bits can send by Electricity, Light & Radio Waves	Ethernet use Electric signals to send bits, is cheap and loss of signal can happen
			Fibre Optic cables use light to send bits, which are very expensive and no signal loss can happen
			Radio Waves, use in Mobiles, Wifi routers, convert digital data into radio waves of diff. frequency and receiver reconvert it into digital data, this technique works on short range

20	Packets & Traffic Managers Routers (Packets)	Small piece of information in the form of bytes is called packet and data sent on internet is in the form of many no. of packets who are having “From IP address” & “To IP Address” & “Total no. of packets for one call” and “current packet number”. Usually the packet size is 1024 bytes = 1Kb	Special computers on the internet called routers and act as traffic manager which directs the packets to destination computer according to best possible route available
	Packet Structure	Header, Payload, Trailer >	Header: containes Metadata (a set of data that gives information about other data) like : To & From IP address, Packet Sequence number, Protocol (type of Data), Total Packet nos
			Payload: have the actual data transfer to/get from server
			Trailer: Packet end information & error checksums data (add up value of all the 1s in payload)	if the error checksum data does not match to the computation value of server then receiver request sender to resend that missing packet

21	TCP (Transmission Control Protocol)	Provide reliable, ordered/sequencial, error checked stream/packets of bytes b/w client & Server	TCP checks whether all packets received or not out of total data sent and provide feedback to sender server so that server can resend missing packet if any	First Handshake and then Data Transfer > 3 Way Handshake to establish connection b/w client & host before data flow: Synchronize (1way connection request from client), Synchronize (2way connection requestion from Server)+Acknowledge(for 1way request by server), Acknowledge(2way request by client). Thus 2 way communication setup
		7 Layers of OSI Model (Open Systems Interconnection) >	Application Layer >	This is the application where user generates or gets data
			Presentation Layer >	Data Encryption happened at this layer
			Session Layer >	Maintains connection and is responsible for controlling ports and session
			Transport Layer >	This is the level where data is divided into packets and numbered to create a sequence. The transport layer determines how much data must be sent, where it should be sent to, and at what rate. It ensures that data packets are sent without errors and in sequence and obtains the acknowledgment that the destination device has received the data packets
			Network Layer >	Decide path at which data will travel, is responsible for sending packets from a network and controlling their movement across a network
			Data Link Layer >	The Data Link Layer is responsible for node-to-node data transfer and error detection and correction.
			Physical Layer >	Transmit bits over the physical medium like cables, wireless etc

22	Security implemented on TCP (SSL)	SSL (Secure Socket Layer) > Developed by Netscape	First Encription, Authentication check of Server, encription key sent to Receiver to Dycript & Data Transfer	Authentication Check: TCP Check the digital certificate (issued by certification authority for verified content) of the website/server and warns you if not found, Then after start transfering of encrypted Data. Secure connection alias as HTTPS
				Encryption Method is CAESAR’s CIPHER used like A+3=D is the actual letter and 3 is the key which only sender and receiver can know. This is symeteric Method
	TLS	TLS (Transport Layer Security) >	First Encription by private key, Authentication check of Server, public encription key received from server, private key encripted by public key and sent to Server, it Dycript there and then pvt key used to dycript data & finally Data Transfer start	Asymeteric Method use Public & Private Key Encryption
			Authentication Certificate of server have public Key + certificate issue public which verify the client before to transfer private key to server	Sender use Public key and receiver have private key to decript
23	Data Transfer Protocol according to Media Type	HTTP / HTTPS (Hypertext Transfer Protocol for Webpages)
		FTP / SFTP (File transfer protocol)
		SMTP (Simple Mail Transfer Protcol)
		POP (post office protocol)
		IMAP (Internet Message access protocol)
		PPP (point to point protocol)

24	Internet Engineering Task Force (IETF)	The IETF is a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. It develop all the internet standards

25	Network enabled technologies (NET)	Technologies that work accros/with the Internet

26	Network Interface Card (NIC)	Hardware circuit which makes possible for a computer to connect to Network	Every NIC has a hardware unique address that is known as MAC Address	MAC Addresses are linked to the hardware of network adaptors
	Organizationally Unique Identifier (OUI) >	Manufacturers place a special number sequence (called the Organizationally Unique Identifier or OUI) in the MAC address that identifies them as the manufacturer. The OUI is typically right at the front of the address.	For example, consider a network adapter with the MAC address “00-14-22-01-23-45.” The OUI for the manufacture of this router is the first three octets—”00-14-22.” i.e. DELL

	Medium Access Control Address (MAC)	It is the unique number asigned to hardware of computer by manufacturer. 48 Bits. The MAC address is a string of usually six sets of two-digits or characters, separated by colons.	Because a MAC address is a unique address, devices on a network do not share the same MAC address.	Because of the potential of tracking wireless devices by using a MAC address, many manufacturers (e.g. Apple, Google and Microsoft) generate random MAC addresses.
	MAC Filtering	MAC filtering is a security measure to prevent unwanted network access by hackers and intruders.	In MAC address filtering, the router is configured to accept traffic only from specific MAC addresses. This way, computers whose MAC addresses are approved will be able to communicate through the network—even if they were given a new IP address by DHCP.

	Address Resolution Protocol (ARP)	is a communications protocol that is an important part of IP (Internet Protocol). ARP maps a 32-bit IP address to a MAC address. 48 bit

27	Ports	this is a connection point through which specific data can be transferred between a computer and other devices thru ip address	A port is a virtual point where network connections start and end. Ports are software-based and managed by a computer’s operating system. Each port is associated with a specific process or service. Ports allow computers to easily differentiate between different kinds of traffic: emails go to a different port than webpages, for instance, even though both reach a computer over the same Internet connection.
	Port Number	Is a way to identify a specific process/service thru which network message is to be forwarded when arrives at server	Ports 20 and 21: File Transfer Protocol (FTP). FTP is for transferring files between a client and a server.
			Port 22: Secure Shell (SSH). SSH is one of many tunneling protocols that create secure network connections.
			Port 25: Historically, Simple Mail Transfer Protocol (SMTP). SMTP is used for email.
			Port 53: Domain Name System (DNS). DNS is an essential process for the modern Internet; it matches human-readable domain names to machine-readable IP addresses, enabling users to load websites and applications without memorizing a long list of IP addresses.
			Port 80: Hypertext Transfer Protocol (HTTP). HTTP is the protocol that makes the World Wide Web possible.
			Port 123: Network Time Protocol (NTP). NTP allows computer clocks to sync with each other, a process that is essential for encryption.
			Port 443: HTTP Secure (HTTPS). HTTPS is the secure and encrypted version of HTTP. All HTTPS web traffic goes to port 443. Network services that use HTTPS for encryption, such as DNS over HTTPS, also connect at this port.
			Port 500: Internet Security Association and Key Management Protocol (ISAKMP), which is part of the process of setting up secure IPsec connections.
			Port 587: Modern, secure SMTP that uses encryption.
			Port 3389: Remote Desktop Protocol (RDP). RDP enables users to remotely connect to their desktop computers from another device.

28	Kernel	a computer program at the heart of an operating system that controls everything else in the system.
	Driver	this is a program that operates or controls a particular type of device that is attached to a computer; each device has its specific driver.

29	Firewall	this is a software that helps to protect your computer from exchanging info to harmful network; it blocks unauthorized access while permitting authorized communication.

30	Data Tables	Is a format to store information in the form of columns and rows in database
	Hypertext	It is the text which displayed on screen thru HTML
	Hyperlink	It refers to other text/Media which reader can immediately access from Hypertext documents interlinked by hyperlinks

31	Button Vs Hyperlink	Button	Hyperlink	Text Field
		In case of Navigation, button does 2 actions. This means send data to save and then Navigate to next page	Its goes to next page w/o submitting anything	Takes in text to submit to server

32	Vector Graphics	are the images or video made up of lines and shapes which defined mathematicaly. This means that they can be scaled up or down without losing any quality. These can be create and displayed by Adobe Flash (extention of flash file .SWF). These are less in size and used to display over web	The most common vector file types are SVG, AI, EPS, PDF, and CRR.