What is computer security?

Many people believe that computer security is about making sure nobody can gain unauthorized access to your computer. While this is partially true, it's not complete. Computer security may be more broadly and usefully defined as whatever measures are needed to make sure your computer behaves as expected.

While this includes making sure that vandals don't damage your computer or make it do things you don't want it to do, it includes making sure that your computer remains under your control and isn't affected by things like data loss and snooping.

Before beginning, it is important to understand three key principles about computer security:

There is no such thing as perfect security. The only computer that can't be broken into is one with the motherboard, power supply and hard drive removed and the case filled with cement.
Security and convenience are opposites. It is best to think of security as a gradient with "convenient" at one end and "extremely inconvenient" at the other.
Security decisions must reflect worst-case scenarios. A computer environment can have many different levels of security for different circumstances and situations. The key question must always be: "what is the worst that could happen if security were compromised in this context?" Security levels should be adapted and changed according to the answer(s) to that question.

Next: Types of security issues in computing