Asked by: Lillian Guainiere, Rye
Computer files are stored as lots of ones and zeros. An ordinary delete operation will either just move the file to a new area called ‘Trash’, or it may make the computer forget where the file is, without removing the file. Even reformatting a drive may not work because it’s like removing the table of contents in a book – all the pages of words are really still there. You may need special software to permanently delete files. This software will overwrite those pesky ones and zeros, setting them all to zero or to random values. When you’ve done that to a file, it ceases to exist, and the data is gone forever.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
