Scareware programs are virus programs designed with the intent to scare the user, into either buying a product or another act. They are usually not malicious, and are usually jokes that don't make any changes to the registry. Many scareware programs are also rogue software or joke programs.
Scareware is usually found in websites, the user may find this in forms like 'Quickly go download this program to get rid of this virus!' This is usually not true as some of the viruses mentioned in these scareware websites are fake and made up to scare the user into buying or downloading a malicious or PUP program.
The scareware is usually found after visiting a website that is for a private or sketchy software.