Real-time protection, on-access scanning, background guard, resident shield, autoprotect, and other synonyms refer to the automatic protection provided by most antivirus, antispyware, and other antimalware programs, which is arguably their most important feature.This monitors computer systems for suspicious activity such as computer viruses , spyware, adware, and other malicious objects in 'real-time', in other words while data is coming into the computer (for example when inserting a CD, opening an email, or surfing the web) or when a file already on the computer is opened or executed, in other words loaded into the computer's active memory.