What ID3 tags are
An MP3 has two parts: the audio, and a small block of text and images that describes it. That block is the ID3 tag. It holds the title, artist, album, genre, BPM, key, comment, cover art, and a few dozen other fields.
Tags are not the filename. You can rename "track_01.mp3" to anything you like and the title inside stays the same. That's why a folder can look tidy in your file browser and still show up as a mess of "Unknown artist" in DJ software, which reads the tags, not the names.
One more thing worth knowing: most DJ software reads tags once, when you import a track, and keeps a copy in its own database. Edit the tags later in another program and the DJ software may keep showing the old values until you tell it to re-read the file.
ID3v1, v2.3, and v2.4: what's the difference
ID3 has gone through several versions. You'll meet three of them:
| Version | Where it lives | Text | In practice |
|---|---|---|---|
| ID3v1 | The last 128 bytes of the file | Western letters only (Latin-1), 30 characters per field | Very old, no BPM, no key, no cover art |
| ID3v2.3 | The start of the file | Unicode supported (UTF-16) | The most widely read version, by both software and DJ players |
| ID3v2.4 | The start of the file | Adds UTF-8 and multiple values per field | Newer and cleaner, but some older gear reads it poorly |
A single MP3 can carry an ID3v1 tag and an ID3v2 tag at the same time, and some files also have an older APE tag at the end. Each program picks the one it prefers, which is the root of many "why does this title look different over here" moments.
If you're unsure, ID3v2.3 is the safe choice: almost everything reads it. Whatever you pick, stay consistent across your library.
The tag fields DJs actually use
ID3v2 stores each field in a "frame" with a four-letter code. You never need to type the codes, but they help when two programs disagree:
| Field | ID3 frame | What to put in it |
|---|---|---|
| Title | TIT2 | The track name, plus the mix in brackets, like (Extended Mix) |
| Artist | TPE1 | One consistent spelling per artist |
| BPM | TBPM | A whole number, like 128 |
| Key | TKEY | One format for the whole library, like 8A or Am |
| Genre | TCON | Short and consistent, or your own categories |
| Comment | COMM | Notes for yourself: energy, set role, vocal or not |
| Cover art | APIC | A square image, usually 500 to 1,000 pixels wide |
| Remixer, Label, Year | TPE4, TPUB, TDRC | Handy for filtering and for crediting tracks |
Two details catch people out. The ID3 standard defines BPM as a whole number, so a value like 127.98 may be read differently by different programs, or rounded. And key has no single agreed format: one program writes "Am", another "A minor", another "8A". Pick one and convert everything to it. If you're not sure which to pick, read what the Camelot wheel is.
How FLAC, WAV, and AIFF tags differ
The name "ID3" belongs to MP3, but the idea is the same everywhere. Each format just stores tags its own way:
- FLAC uses Vorbis comments: simple pairs like TITLE=…, ARTIST=…, always in UTF-8, so accented letters are rarely a problem. Field names are free-form, so key is often stored as INITIALKEY but sometimes as KEY. Cover art sits in its own picture block.
- AIFF stores an ID3 tag inside the file, so it behaves almost exactly like MP3. That's one reason many DJs who want lossless files with reliable tags choose AIFF.
- WAV is the messy one. It can carry an old-style INFO list with only a handful of fields, an ID3 tag, both, or neither. Support differs from one program to the next, so a WAV that looks perfect in one place can show a blank title in another.
If you're still choosing a format, MP3 vs FLAC vs WAV covers the sound side. For tags alone: MP3, AIFF, and FLAC are dependable, WAV is a gamble.
Common tag problems
These turn up in nearly every downloads folder:
- Empty tags. The title lives only in the filename, so the DJ software lists the file as "track_final (1)".
- Artist and title in one field. "Artist - Title" crammed into Title, with Artist left blank.
- Garbled Vietnamese characters. Text like "Tình yêu" means the tag was written in one character encoding and read in another. Old ID3v1 tags and programs that save in a local, non-Unicode encoding are the usual cause.
- Each program shows something different. One reads ID3v2, another the leftover ID3v1 or APE tag, a third the WAV INFO list. Fix only one of them and the others keep the old text.
- Genre shows up as a number. Values like "(13)" are old references to a fixed genre list from ID3v1, which some software doesn't translate.
- Comments full of ads. Website addresses and phone numbers left by whoever shared the file.
- Huge cover art. An image of several megabytes in every file bloats the library and can slow some players.
Most of these share one fix: write the tags again, cleanly, in Unicode, with one version and one format for every file.
Why clean tags matter when you play
At home a messy tag is an annoyance. In the booth it costs you a transition. You have maybe 30 seconds to find the next track, and you search by typing a few letters of the title or artist. If the title is empty or misspelled, the track might as well not exist.
On a DJ player reading from a USB stick, you browse and sort by tags too: by BPM, by key, by artist. A missing BPM means the track drops to the bottom of the list. Screens are small, so a title stuffed with "(Official Audio) www.site.com" cuts off the part you need. Cover art helps more than you'd expect: under pressure you recognize a picture faster than you read a word.
FAQ
Should I use ID3v2.3 or ID3v2.4?
ID3v2.3 if you want the widest compatibility, especially with older DJ players. ID3v2.4 is fine if every program you use reads it. The worst option is a mix of both across your library, so choose one and stick with it.
Do ID3 tags affect sound quality?
No. Tags sit in a separate block of the file and never touch the audio. Editing tags changes the file size slightly, mostly because of cover art, but the sound stays exactly the same.
Why do Vietnamese characters show up garbled in my tags?
The tag was saved in one character encoding and is being read in another, often an old ID3v1 tag or a program that didn't save in Unicode. Retype or rewrite the field in a Unicode-aware tag editor, and remove any old tag on the file that still holds the broken text.
Does renaming a file change its tags?
No. The filename and the tags are separate. To keep them matching, rename files from their tags, or fill tags from the filenames, with a batch tool rather than by hand.
Faster with Taxonomy DJ
The batch tag editor in Taxonomy DJ fixes tags for a whole folder at once:
- Drag a folder onto the Tags tab, or click Browse folders or Choose from library.
- Select one or many tracks, edit any of 30 fields (Title, Artist, Key, BPM, Genre, Comment, Remixer, Label…) in the left panel, then click Save. Right-click the cover art to set or remove it for every selected track.
- For bigger cleanups, click Action groups ▸ New group and add steps like Clean up (remove links, website names, and phone numbers), Round BPM, Convert key between 8A and Am, or Set tag. Click Apply group ▾ and check the before-and-after preview. Nothing is written until you confirm.
It handles MP3, WAV, FLAC, and AIFF. Tags are written in Unicode, a file's ID3 version is kept (v2.3 stays v2.3), and if an MP3 still carries an old APE tag, its matching fields are updated too, so other software stops showing the stale text. The Tags tab is part of Premium; BPM and key detection in the Music Library tab is free on every plan.
Read next: how to batch edit MP3 and FLAC tags and an easy batch MP3 tag editor, no syntax to type.