"Junk files" refers to unnecessary or useless files that accumulate on a device, taking up storage space and potentially slowing down its performance. Full definition
They are good and safe utilities that will help you remove your unwanted junk files in a few clicks. (thewindowsclub.com)
There are a number of security apps you can download to help protect your phone, scan for viruses, and get rid of junk files and any potentially infected software. (digitaltrends.com)
Clean common system junk files, as well as invalid registry entries. (neowin.net)