This can better prevent misjudgment of file format, and feature signature can give more detailed file format information. The disadvantage of this method is its low efficiency. Especially when displaying a large number of files, because each signature has a different recognition method, judging the file format will consume a lot of system resources. The extension and metadata schema mentioned later can be matched quickly because they are data in a fixed format. Applications usually use feature signatures to determine whether a file is complete and valid.