Have the feeling that you're being watched every time you use your computer? It may well be just that—a feeling—but it's worth your time to take a few steps to protect yourself. While there are a number of ways someone could spy on your computer, it only takes a few steps to disable most of the common techniques.
Run a virus and spyware scan. Some examples of viruses and spyware can leak information about you to the programmers who created them, compromising your security and, in some cases, your identity. If you don't already have software that scans for viruses and spyware, check out Microsoft Security Essentials. This free software from Microsoft can help protect your computer from such risks.
Enable a firewall, if you haven't already. If anti-virus and anti-spyware software is like the police protecting your computer, a firewall is like the border security guard. Firewalls deny access to your computer by unauthorized programs, which means unauthorized computers can't access your data over the Internet. If you don't have a firewall installed, you can enable the Windows Firewall. Click "Start," then "Control Panel," then "Windows Firewall" to configure it.
Check for keyloggers. These can take two forms: physical or software. Checking for physical keyloggers is simple: Follow the cord of your keyboard all the way to your computer. If you find a device you don't recognize between your keyboard and your computer, it may be a hardware keylogger, designed to record your keystrokes for someone to retrieve later.
Checking for software keyloggers is best done with software designed to find them. Check out KL-Logger (free download), which can scan your computer for such software.
Check your system tray for unfamiliar icons, and close programs you don't need. Any software called "VNC" is designed to let people see what's on your screen and control your computer remotely; close this software if you're not sure why it's there.
Most of these steps apply only to Windows computers, because that operating system is the most vulnerable when it comes to security. Firewalls, for example, are built into Mac and Linux-based systems, and viruses are rare on those platforms. Hardware keyloggers could exist on either platform, however. It never hurts to check.