Computer security is the means of preventing and detecting unauthorized use of the computer network, where prevention measures help web design firm   to stop unauthorized users from accessing the network. This is a branch of technology known as information security as applied to computers, where information security means protecting information and information systems from unauthorized use, disclosure, disruption, modification, or destruction.
 
Viruses usually begin to spread before they are identified, and the only way they are identified is when someone discovers their computer is behaving incorrectly and then they realize they have a virus. Viruses are usually hidden in programs and activated when a program run. They also can be attached to certain other types of files, such as email attachments and video files.
 
Web sites use cookies to "remember" your details, such as your user name or site preferences, in order to personalize your web site experience. The web browser transmits information back to the site each time you view that site until the cookie expires. Web visitors that have spyware and trojans installed on their computers, are examples of malicious software, referred to collectively as malware.
 
Securing a computer system is a complex issue touching several disciplines, departments, and cultures. Investments in these technologies should be followed up with investments in personnel training, strict policy enforcement, and periodic review of the overall security policy. Computer security and resilience is an exciting topic because the challenges and the technology evolve on a daily basis, where the skills needed to keep up with this rapidly expanding field are varied and provide a platform on which a graduate can build a career in any area of the computing industry. Computer security could be seen as a subfield of security engineering, which looks at broader security issues.