How to identify a computer virus

Here we will identify a virus.
First lets discuss the type of viruses:

1. Trojan
2. Worms

Trojan- A trojan is human triggered virus which means human interaction is necessary for executing               a virus. Trojan nor harms your computer neither take any space. It just do its work and melt.

             Its work is opening the backdoor in your computer by which a hacker can access your                         computer and damage your data or steal it.

Worms- Worms are self triggered. They do not need any human interaction. They can be transferred

              by just connecting any storage device.

In above image you can see there are two image files with the same name and same icon. The only diffrence is extension . one is exe and one is png . Png is an extenion for image file . Exe is extension for executable files mostly used for setups.

exe file is the virus file.