Security software can serve a number of security functions. Some programs are designed for a single and specific purpose, such as spyware removal, while others can accomplish several functions. Security software is used to establish firewalls, to detect and remove viruses, to secure information on a network, to detect attacks on a computer or network, and so forth. As a general rule, it runs all the time, providing background protection, and users can also run utilities to scan their computers for specific computer threats. Such software can also be used for access filtering. With some computers and networks, access filtering may be desired to keep people away from sites which could threaten security, such as sites which automatically start downloads of malicious code. Access filtering may also be utilized to ensure that people in the workplace only access work-appropriate sites, and to protect young computer users such as children from material which could be threatening or dangerous.