CCleaner is the number-one tool for cleaning your Windows PC. It protects your privacy online and makes your computer faster and more secure. .CCleaner is our system optimization, privacy and cleaning tool. It removes unused files from your system - allowing Windows to run faster and freeing up valuable hard disk space. It also cleans traces of your online activities such as your Internet history. Additionally it contains a fully featured registry cleaner. But the best part is that it's fast (normally taking less than a second to run).