MusicBrainz Picard can batch modify ID3 tags and automatically tag MP3 files.
For those of us who have collections of mp3 files dating back decades or for those who simply have a huge collection of mp3s, it can sometimes be difficult to find exactly what you're looking for. To make things easier, MP3 files support something called ID3 tags which contain information about the Artist, Song Title, Album, Album Year and more.
ID3 mp3 tagging tools generally provide added functionality, yet only a few of them offer batch editing tools which modify multiple files at once, saving you time. These tools are able to perform batch operations on selected files and folders and give users customizations in how their ID3 tags appear in programs like Winamp or iTunes.
The best of these tools will generally connect to online databases such as FreeDB or CDDB, which can also download album cover art which normally display on devices such as iPad, iPhone, Playstation 3 and Xbox.