Spyware installed on a computer without the user's knowledge which gathers personal information and/or showing the user ads. Spyware has a range of meanings including malware, browser parasites, unsolicited commercial software, scumware, homepage hijackers, dialers, and trojan horses. Spyware logs the information such passwords, email addresses, web browsing history, online buying habits, the computer's hardware and software configuration, the name, age, sex, etc of the computer that infected with spyware.
Use anti-spyware/anti-adware program to run a spyware detection and spyware/adware removal program weekly. Use firewall program and anti-virus/anti-spyware/anti-adware program, they are usually store in your computer tray to perform the real-time check. Make sure they are run together, and updated regular.
Some similiar software, example the computer surveillance software, is different than spyware, it is useful for you to monitor your computer to keep an eye on the people who are using your computer by recording every activity on your computer done by someone else.