Virus protection software can be installed on a computer to detect and try to remove any viruses.

Computers connected to networks - especially the Internet - need to be protected from hackers. Firewalls are software methods of blocking access to anyone from outside a network unless they are authorised.

Any stored data file has file attributes that can be set. The commonly used ones in Windows are:

• Read-only - the file can be read but not altered
• Hidden - the file is not displayed in listings of files.

To maintain file security when data is transferred from one computer to another the data can be encrypted.

This means that the data is encoded in some way before it is sent, and therefore meaningless to anyone intercepting the message. The data is then decoded at the receiving end by the user who knows the way to decrypt it (often referred to as the key).

Data encryption can also be used when data is stored on a file. A hacker accessing the data will find it meaningless unless he has the key.