Windows Registry is the database in which windows stores all the information about the softwares installed in your system. Windows access this registry to access all the info about the softwares installed in your system. When you install a software, entries about the software is made in the registry. When the software is uninstalled these entries are removed.
If you uninstall programs or softwares, it should ideally delete all the entries made in the registry. But due to crappy softwares, in which un-installation has not been done perfectly, entries remain in the windows registry even after the uninstalling the software.
You need to do this manually, so that registry is well maintained. In maintaining the registry, not only the chances of system crashes are reduce but also it improves the overall system performance.
NOTE: You should not manually edit the entries in the registry as it may cause the system to crash up or at times it may even refuse to startup
There are several tools available for cleaning the windows registry. CCleaner (www.ccleaner.com) tools does a pretty good job in cleaning the unwanted entries in the registry.
After starting CCleaner
1. Click on the “Registry” or “Issues” button.
2. Select all the items in the “Registry Integrity menu”.
3. Click on “Scan for issues Button”.
4. The program will now scan the registry and display all the undesired entries.
5. The click on the “Fix Issues” to delete them from the registry.
Take time to look at the entries shown in the list as it may display some of the entries that are needed by the programs
Always make sure to take a backup of the registry before the process, to recover in case of any disaster.