Antivirus software

Antivirus software detects, blocks and removes malicious programs, collectively known as malware. The term covers computer viruses, which attach themselves to files and spread when those files are shared, along with worms, trojans and other harmful code. Such programs may damage data, steal information or take control of a machine, and because new threats appear constantly, antivirus protection is a standard part of keeping a computer safe.

Detection relies on two complementary methods. Signature scanning compares files against a database of patterns drawn from known malware; it is reliable for threats that have already been identified, which is why the signature database must be updated frequently. Behavioural or heuristic analysis watches for suspicious actions, such as a program trying to modify system files or spread itself, and can flag new malware that no signature yet describes. Most products combine the two, and many add real-time protection that checks files as they are opened or downloaded rather than only during a scheduled scan.

Some services offer an online virus scan, run through a web browser, which can give a second opinion without installing a full product, though it generally cannot provide continuous background protection. Antivirus tools are distributed in several ways: as commercial products, as shareware that can be tried before buying, and as freeware versions suitable for home use. Whichever is chosen, the key to effective protection is keeping the program and its definitions up to date, since out-of-date software cannot recognise the latest threats.

Frequently asked questions

How does antivirus software detect threats?

It compares files against a database of known malware signatures and also watches for suspicious behaviour, which lets it catch both known threats and some new ones.

Why must antivirus software be updated so often?

New malware appears constantly. Signature-based detection can only recognise threats already in its database, so frequent updates are needed to stay effective.

What is an online virus scan?

It is a scan run through a web browser without installing a full product. It is useful for a second opinion but usually cannot provide continuous background protection.