Computer
A computer is an electronic device used to process data
A computer system consists of hardware and software components.
Hardware is the physical equipment such as the case, storage drives, keyboards, monitors, cables, speakers, and printers.
Software is the operating system and programs. The operating system instructs the computer how to operate. Programs or applications perform different functions.


Central Processing Unit (CPU)
CPU is known to be the brain of the computer system.
It performs functions like calculations, decisions, control all units etc.
In the CPU, the primary components are the ALU (Arithmetic Logic Unit) that performs mathematical, logical, and decision operations and the CU (Control Unit) that directs all of the processors operations.

Components of Computer
Input Devices
Input devices used to enter data or instructions into a computer
Ex: Keyboard, Mouse, Digital camera, Scanner, Mic, Bar code reader, Joystick
Output Devices
Input devices used to receive or display output from a computer
Ex: Printer, Monitor, Projector, Speaker

Storage Devices
Operating System (OS)
The operation of a computer is controlled by a software known as Operating System
The OS directs the input and output of data, keeps track of files and controls the processing of computer programs.
The OS serves as an interface between the computer and user.

Paint (Software)
Paint (formerly Paintbrush for Windows) is a simple graphics painting program that has been included with all versions of Microsoft Windows. It is often referred to as MS Paint or Microsoft Paint.
The files are saved with extensions .jpeg, .gif, .png, .tiff

MS OFFICE
MS Word
Word processing program that allows user to type and save documents.
File extensions are .doc, .docx

Command Shortcut
Undo Ctrl+Z
Cut Ctrl+X
Copy Ctrl+C
Paste Ctrl+V
Select All Ctrl+A
Find Ctrl+F
Replace Ctrl+H
Print Ctrl+P
Save Ctrl+S
Help F1

MS Excel (Spreadsheet)
It is an electronic document in which data is arranged in rows and columns.
File extensions are .xls, .xlsx
Image
Worksheet: a grid of horizontal rows and vertical columns.
Workbook: contains one or more worksheets.
Column: vertical arrangement of cells. Named by English alphabets.
Rows: horizontal arrangement of cells. Named by numbers.
Cell: intersection of rows and columns.
Cell address: identifies location of the cell. Ex: A1, B3, E2, G5
Formula: to insert a formula, entry should begin with an = operator.

Network
A computer network is an interconnection of various computer systems located at different places, for the purpose of communicating data and sharing resources.
Types of Networks
Local Area Network (LAN): Networks used to interconnect computers in a single room, rooms within a building or buildings on one site
Wide Area Network (WAN): WAN describes a computer network spanning a regional, national or global area

Metropolitan Area Network (MAN): A MAN typically covers an area of between 5 and 50 km range. Many MANs cover an area the size of a city, although in some cases MANs may be as small as a group of buildings

Internet
The internet or simply called "the net" is a worldwide system of computer network.
The Internet carries an extensive range of information resources and services.
WWW  or web is a collection of information containing various sites , pages, pictures and sound effects
WEB : A term used to represent the collection of information
WEB PAGE : Each individual page of a website is called web page
WEBSITE:  A web site is located on the internet.  It is a collection of Web files on a particular subject that includes a beginning file called a Home page
WEB SERVER : A web server is a program that generates and transmits responses to clients request for web resources
WEB BROWSER : Browser is a software application used to enable computers users to locate and access web pages. Ex: Chrome, Firefox, Internet Explorer

Search engines
It is a technique used to find information on the internet.
To search information on the internet search engine is required.
Ex: Google, Yahoo, Bing

Social networking sites
Social media site is a website that doesn’t just give you information but also interacts with you.
Ex: Facebook, Instagram, Twitter

Electronic mail (E-mail)
Email is an electronic message transmitted over the Internet or computer network from one user to another.
It consists of text and can include file attachments. Attachments could be pictures, documents, spreadsheets, audio files, video files, etc.

Email Message Format
From: Shows a sender’s email address
To: Shows a recipient’s email address. This can be more than one.
CC: (Carbon copy) Email addresses of other people who have been sent a copy of the email. The recipients of the email can see all of the email contacts to whom the copies have been sent.
BCC: (Blind carbon copy) Email addresses of other people who have been sent blind carbon
copies of the email. The recipients of the email do not know that the same email has been sent to other email address in BCC.
Subject: Shows the topic of the message
Message body: The body consists of the text message and any attachments to be sent.

Information Security
Information security sometimes shortened to InfoSec is the practice of defending information from unauthorized access, use, disclose, disruption, modification, inspection, recording and destruction.

Cyber Crimes
Cyber crime refers to any crime that involves a computer, mobile and a network.
The computer may have been used in the commissioning of a crime or it may be the target.

Types of Cyber crimes
Cyber terrorism, Cyber stalking, Sale of illegal articles like narcotics, weapons and wild life etc., Online gambling, Intellectual property crimes, Email spoofing, Forgery, Phising, Credit card fraud

Virus
A virus is a program that can infect other programs by modifying them to include a possibly evolved copy of itself.
Antivirus
Antivirus software is a computer software used to prevent, detect and remove malicious computer virus. Antivirus program scan a computer system for virus files and then allows that system user's to deal with those files.