Spyware is easy to spot, especially when there's a lot of spyware installed on a computer. Here are some symptoms:
Sluggish PC performance Spyware takes up computer memory and can bog down performance.
Weird pop-up ads If lots of pop-up ads start to appear on your computer even if you are not surfing the Internet, chances are you have adware on your computer.
New toolbars you can't delete If a strange toolbar appears on your desktop or in your web browser and won't go away, it's probably spyware.
Unexpected changes to your homepage settings If your web browser starts opening to a web page you've never seen before, your computer is likely infected with a browser hijacker.
Internet connections go awry If one day you can no longer connect to the Internet, it could be because spyware has been messing with your connection settings.
Unusual search results When you search for something on the Internet, a strange or unexpected search site produces results. Your web browser has probably been redirected by spyware to a search engine of its choosing.
Software malfunction If a program you use was working fine and then one day it won't start or it produces weird errors, it could be that spyware has corrupted files it requires to run or messed with the way it works.
Frequent computer crashes Spyware can cause a computer to crash either because a system is overwhelmed or because the spyware programming is badly written and causes the crashes.
Macintosh computers don't have the same problem with spyware as PCs. Each software install on newer Macs (which run the operating system called OS X) requires a user to type a password for the installation to continue, so self-installing spyware is stopped . That said, there has been spyware created for the Mac and it can find its way on to your Mac when you install legitimate software. It's safe to say that spyware is not a problem on the Mac, while on PCs it's a plague. But do note that snoopware for the Mac does exist. Cookies are also a feature of web browsers on the Mac, too.