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Our simple guide to some of the terms used in our advice on Internet security and protection.

• File Extension
• Firewall
• Hackers
• Keystroke Loggers
• Phishing
• Spyware
• Trojans
• Viruses
• Virus Definition Files
• Worm

File Extension

The three-letter code at the end of a file name that tells you what kind of file it is. Double extensions are often used to conceal viruses.

Firewall

Software application and/or Hardware, which prevents unauthorised access to your computer from the Internet and prevents unauthorised programs sending information from your computer.

Hackers

A term used to define an individual(s) who attempts to gain unauthorised access to computer systems for the purpose of stealing and/or corrupting data.

Keystroke Loggers

Software that captures the keys pressed on your computer keyboard and sends a log of these to the hacker via the Internet. Used to capture your passwords and often included in Trojans.

Phishing

The use of 'spoofed' e-mails and fraudulent websites which are designed to trick recipients into divulging personal financial data such as credit card numbers, account usernames and PINs/passwords.

Spyware

Software installed as part of another application which is designed to monitor and report back on activity on a computer. Often installed without the users knowledge. May also be called scumware, adware or malware.

Trojans

An apparently harmless program that contains malicious code designed to give control of your computer to a hacker. Can be used to record keystrokes (see keystroke logger) and delete files or even view your screen contents.

Viruses

Software disguised as something else that can cause damage to data and systems. Often spread as email attachments or files hidden in disks.

Virus Definition Files

The list of known viruses that anti-virus software searches for on your computer or incoming files and emails. In order for anti-virus software to work effectively it is vital that you should keep your virus definition files as up to date as possible.

Worm

Similar to viruses in that they are programs that are often designed to interfere with the computers they infect. They don't attach themselves to files or other programs but spread automatically across networks of computers.