Audio Formats Explained: When to Use MP3, WAV, FLAC, OGG, and AAC

A coworker sent me a .flac file last week and asked me to add it to a web project. My first reaction was "just convert it to MP3." But then I stopped and thought about it. Why MP3? Is it actually the best format for web audio in 2026? The answer, like most things in engineering, is "it depends." And the reasoning matters more than the answer. Audio formats are a tradeoff between file size, quality, compatibility, and licensing. Choosing the wrong format means either wasting bandwidth, losing quality, or breaking playback on certain devices. Here's what each format actually is and when to use it. Lossy vs lossless: the fundamental split Audio compression falls into two categories. Lossy compression permanently removes audio data that the algorithm determines is inaudible or less important. You get smaller files, but the removed data is gone forever. Re-encoding a lossy file makes it worse -- each generation loses more data. MP3, AAC, OGG Vorbis, and Opus are lossy formats. Lossless comp