Security technical FAQs

Understand the software that keeps you safe online

Staying secure online involves a few simple pieces of computer software. These FAQs explain the software and other common terms you'll come across.

1. What does anti-virus software do?

Anti-virus software detects and eliminates viruses from your computer. If you use anti-virus software, you should regularly download updates from the company that made the program — often you can set these to download automatically. This will help protect your computer from the latest virus threats.

2. What is a firewall?

A personal firewall is a piece of software that provides a barrier between your computer and the internet. A firewall will prevent unauthorised access to your computer. Firewalls will not necessarily protect your computer from viruses — you also need recognised anti-virus software.

3. What is a certificate?

Websites that let you sign in securely (such as internet banking sites) have to provide a security certificate — this is your reassurance that the site is genuine. If the site does not have a security certificate, your browser will not let you sign in securely.

4. What is a cookie?

A cookie is a tag or marker that a website saves onto your hard disk so that it can remember something about you at a later time. Typically a cookie contains information about your preferences.

For example, some websites let you choose a city as your "home", then offer you tailored information about that city. These websites will put a cookie on your hard disk so they can remember this information for next time you visit.

5. What is encryption?

Encryption means using a code to change data into a form that can't be understood. When information is encrypted it can be sent securely online, because it can only be read with a particular decryption code. Decryption is the process of converting encrypted data back into its original form, so it can be understood.

6. What is a Secure Socket Layer (SSL)?

SSL is a common method of encryption that allows you to send and receive information securely over the internet. Many websites use SSL to secure customer information such as banking details.

Normally you will not be aware of SSL — it works automatically when your web browser accesses a secure web site. You can tell if you're in a secure website by looking the address bar of your browser — the address will begin with "https:" rather than "http:". If you use Internet Explorer, you'll also see a closed padlock at the bottom right-hand side of your browser window.