A virus is a program that makes the computer slow and causes trouble.
- Without the user’s knowledge, the program gets replicated itself by making multiple copies.
 - Viruses can be shared across globally which can affect numerous systems when connected to the internet.
 - There are chances where your computer can be hacked.
 
Why are they called Virus? 
 
 
- Computer viruses are called viruses, as they share some of the traits similar to biological viruses.
 - Like a biological virus passes from person to person, even computer virus passes from computer to computer.
 - Virus-infected computers can infect other programs or documents.
 
  
How will we know if our computer is virus affected?
- Your system will be slow.
 - It will take time to load programs on your computer.
 - The documents stored in the system get corrupted or deleted.
 - The files get renamed with different names with some extension.
 - There will be frequent unusual error messages on the screen.
 
What are the ways can computer virus spread?
- By opening an infected email link or an attachment from an unknown source.
 - By downloading infected programs from the internet.
 - It can also be transmitted through external storage such as an infected floppy disk, pen drives and CDs.
 
Type of computer virus
- Spyware once installed to a computer, collects information about users without their knowledge.
 
  
- Worm virus cannot get added to other program but it makes copies over and over and uses memory.
 
  
- A trojan horse always does something destructive and are not self-replicating.
 
  
Classifications of Virus
A virus can be broadly classified into three categories:

Anti-Virus Software
Definition –
- We can prevent our computer from virus attack with the help of Anti-virus software.
 - These are programs designed to prevent, detect and remove software viruses.
 
Functions –
- It helps to scan files or directories
 - It allows to schedule scans and it automatically runs to detect the virus
 - It allows to initiate a scan of a specific file of your computer, or of a CD or flash drive at any time
 - Removes any malicious code on detection
 
Ways to avoid the virus attacks –
- Scan all the email attachment before opening them
 - Install your computer with a good anti-virus program to scan for viruses
 - Scan the disk frequently for viruses
 - Never install any pirated software
 
  
Below listed are the important tips on preventing malware safe from infecting your computer.
- Install your system with anti-virus/malware software.
 - The installed anti-virus software to be kept up to date.
 - Schedule regular scans or automatic update of anti-virus software.
 - Secure your network; do not connect with unknown sources.
 - Before opening a link, check for the send and the content.
 - Keep your Information safe.
 - Avoid using free Wi-Fi or connecting to unknown sources.
 - All the files are to be backed up to date.
 - Use a strong password with a combination of alphanumeric.
 
Cyber Crime –
- Cybercrime encompasses any criminal act dealing with computers and networks (called hacking).
 - Additionally, cybercrime also includes traditional crimes conducted through the Internet.
 - For example; Internet fraud, identity theft, and credit card account misuse or usage of a stolen card are considered to be cybercrimes.
 - These are illegal activities which are committed through the use of a computer and the Internet.
 
Backup and Restore –
To back and restore data was introduced by Microsoft Windows in Windows Vista OS and later versions allowed users to create backups and restore from backups.
To back up your files
- Open Backup and Restore by clicking the below
 
Start button >> Control Panel >> System and Maintenance >> Backup and Restore.
- Do one of the following:
 
- If you've never used Windows first we have to backup, click Set up backup, and then follow the steps in the wizard.
 - If you've created a backup before, you can wait for your regularly scheduled backup to occur, or you can manually create a new backup by clicking Back up now.
 
Restore files from a backup
- Open Backup and Restore by clicking the below
 
Start button >> Control Panel >> System and Maintenance >> Backup and Restore.
- Do one of the following:
 
- To restore your files, click Restore my files.
 - To restore the files of all users, click Restore all users' files. If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
 
Recap
A virus is a program that makes the computer slow and causes trouble.
- How will we know if our computer is virus affected?
 - What are the ways can computer virus spread?
 - Type of computer virus - Spyware, Worm, Trojan horse
 - Classifications of Virus - Boot Virus, Program Virus, Macro Virus
 
Anti-Virus Software
Ways to avoid the virus attacks
Important tips on preventing malware
Cyber Crime
Backup and Restore