The term advanced persistent threat (APT) was originally used to describe complex, ongoing espionage perpetrated by foreign governments. However, today, APT typically refers to a category of cybercrime directed toward businesses or government entities. APTs are usually online attacks used to achieve goals beyond those that can be met by a single security breach, but some may involve malicious activity conducted onsite. Compromised computer systems are continuously monitored by the attackers or added to a stable of slave computers to be used to achieve some future goal. APTs are most often perpetrated by employing some form of malware, and IT technicians defend against APTs by installing antimalware software and hardware firewalls.