Washing Machine cleans up files created by web browsers and other programs that access the Internet.
Washing Machine can clean five types of items: Bookmarks, Caches, Cookies, Download Histories, and Browsing Histories. It works with most web browsers, and many utilities or other programs that store information without your awareness. It even cleans up after some programs that you would never think are storing data.
When you surf the web, or use other programs that access the Internet, these programs record where you go and what pages you browse. Your web browser and other programs also store information about you and your browsing in "cookie" files. And many programs store temporary files in "cache" folders that can take up space and slow down your browsing.
Many of these files contain personal information that can be seen by others who use your Mac, or by hackers who gain access to your computer.