Have you ever had new programs installed on your computer, but yet - you didn't install them yourself? You had internet connection a half hour ago, but now you don't after you opened up that new email that was sitting in your inbox for awhile?
Sounds like spyware to me.
A lot of the computer viruses are the same, messing up your computer, taking away or adding programs, not giving you an internet connection - spyware is also one to do things that are listed to your computer.
Spyware is normally not seen by the computer user. Computer viruses like to work behind the scenes. Also like other computer viruses, it strives to collect different types of personal information. It's not very easy to detect spyware. Sometimes keyloggers are installed by the owner of a computer on purpose, so they can secretly monitor other users. They can track the internet surfing habits of a user and keep track of the sites that have been past visited.
Other things that are monitored may be keystroke captures, chat logging, snapshots, email logging, website logging and anything else that you can think of where it would be useful to other companies. Sometimes spyware can redirect web browser activity also.
The programs are usually meant for parents, businesses and similar places, but they can easily be abused if used without your knowledge.
It's not a computer virus that you install yourself. It is a bunch of add-ons that are rather small that you might or might not disable during the install of a program. In many instances, the EULA provides a couple of lines about privacy matters, but most users of a program or download don't stop to read the fine print. Thus, they have no idea that they have a computer virus on their computer.
You would think that anything that uses your information in a way that you don't want would be illegal, but spyware is not an illegal software. There are usually a bunch of different reasons why a user may not agree with and why they may not want to use the product.
Usually this involves the tracking and sending of data that was mentioned before.
Another possibility of getting it would be peer to peer sharing. Someone may install some spyware as part of their standard installation process that will be sent to you and if you don't read the installation list, you may notice that you are getting more then what you bargained for.
Another way to get Spyware into your computer is by the broswer add ons that you see a lot of. Those tacky search bars that fit across the top of your browser. They can be the hardest things to get rid of. Some are riddled with computer viruses, and cause the website to copy what you were searching for and where you went on the internet, and could possibly copy your username, passwords and emails.
Some signs that you may have a computer virus include having ads pop up even when you are offline, you want to go to one website, but instead end up on another website, your computer is dialing up phone numbers by itself, when you search another site handles the search instead of the original and your bookmarks change on their own.