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What is it
AAC is a lossy audio codec designed to replace MP3 — it delivers better sound quality at equivalent bitrates and is the default audio format for YouTube, Apple Music, and most streaming services. MP3's better-sounding successor by every technical metric. AAC is often wrapped in an M4A or MP4 container rather than standing alone as a bare .aac file. Every modern phone, browser, and media player supports it. The only reason MP3 persists is inertia.
Technical details
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What opens it
Every modern media player
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FAQ
What's the difference between AAC and MP3?
AAC sounds better at the same bitrate. A 128 kbps AAC file is roughly equivalent to a 192 kbps MP3. MP3 has broader legacy device support, but every modern device handles AAC fine.
Is AAC the same as M4A?
Not exactly. AAC is the audio codec; M4A is the container that usually holds AAC audio. Think of M4A as the box and AAC as what is inside. You can convert AAC to MP3 with <a href="https://fwip.app/tools/aac-to-mp3/">fwip</a> if you need wider compatibility.
Is AAC lossless?
No. AAC is lossy — it discards audio data to shrink the file. For lossless audio, use FLAC or ALAC. That said, at high bitrates (256 kbps+), most listeners cannot hear the difference.
Related formats