How did Spyware/Adware get on my computer?

Spyware and Adware programs can both be installed on a user’s computer through downloading software from the Internet or from a software virus. The main difference between Adware and Spyware is that Adware is installed with consent from the user by means of acceptance of a User Agreement when a program is downloaded. Be sure to carefully read all information that is presented to you before agreeing to install a program.