Small software developers often try to generate revenue from their free software by bundling third-party software as well as display advertisements into the installer. These third-party software serve no useful purpose other than try to push the user into paying for something they don’t need, such as Windows registry cleaners. Then, there are browser toolbars whose purpose is to gather data about the user’s browsing habits such as the websites they visit, search engine they use and the queries they make. What happens to the data is anybody’s guess. Occasionally, there would be malicious programs that harm the system or consume inordinate amount of resources that makes the computer less responsive.