Antivirus
A program that watches your files and apps and blocks the ones known to be harmful.
An antivirus is software that checks what arrives on and runs on your computer or phone, looking for malware: viruses, ransomware, spyware and the like. It scans files when you download or open them, and when it finds something dangerous it blocks it or moves it to quarantine, a locked area where it cannot run, so you can delete it or restore it if it was a false alarm.
It recognizes threats in two main ways. The classic one is signatures: a constantly updated list of fingerprints of known malware, like a wanted-posters board. The newer one is behavior: watching what programs do, and raising the alarm when, for example, an unknown app suddenly starts encrypting hundreds of your documents. Signatures catch known threats reliably; behavior analysis catches some new ones, at the cost of occasional false alarms.
Today most computers already have one built in. Windows comes with Microsoft Defender turned on, and macOS, iOS and Android check apps in their own ways. In companies the same idea grows into EDR tools that also record what happened on each machine so a security team can investigate.
An antivirus is a seatbelt, not a guarantee. It cannot stop you from typing your password into a fake site, and brand new malware may slip past it. It works best together with habits: keep the system and apps updated, install software only from official sources, and keep backups.
Keep in mind
- Scans files and running programs and quarantines what looks harmful.
- Detects known malware by signature and some new malware by behavior.
- Windows, macOS and phones already include protection; keep it on and updated.
- It does not protect against phishing or bad habits; updates and backups matter as much.
