Antivirus refers to the products and technology used to detect malicious code. Antivirus software can typically prevent malware from infecting your system and it typically can remove malicious code that has infected the system. Most antivirus vendors share information and resources to ensure rapid response to malicious code outbreaks. Legitimate antivirus vendors participate in independent testing which certifies their products to detect and/or disinfect a specific set of malware.
Traditional antivirus software use signature scanning to scan files for malicious code either in realtime, automatically as they are introduced to the system, or as manually requested by the user. Other types of antivirus products rely on integrity checking and/or behavior blocking to respectively prevent files from modificaton or stop certain actions from taking place.