TrID is a tool designed to recognize the file types from their binary signature.
Many times we need to know what kind of file we are handling. For example someone sends an email with an attachment with the .odt extension, and you do not know what program is used to open that file. Thanks to TrID you know what software you need to open that file.
There are other programs that give us information about the file that we do not know but TrID is different, because it has no fixed rules to give us information about the files, as it can be "trained" to recognize new formats in a quickly and automatically way.
Because the database expands with new information, we will never be outdated and we shall know, at all times, the type of file we are using.