When browsing on the web or running an application, a history of your activities is always recorded on the hard disk. When you are on the internet, your browser records the URL adresses, the key words in the search engine, information that you used when registering in the sites, etc...
Whereas under Windows, it records the recent opened files, history of recent folders, used programs, etc...
All these data are stored on your hard disk. Therefore, everybody can spy your activities, and the data encumber your hard disk.
Delete History Free deletes your activity history in some clicks.