- SBC (Subband coding): This is the default codec for all stereo Bluetooth headphones, and it provides the lowest audio quality. It isn't always terrible, but the quality of the stream can vary from device to device, so SBC sometimes sounds noticeably worse than its alternatives.
- AAC: The AAC codec is very efficient, providing better quality than SBC. It's the only non-SBC codec that iPhones and iPads support, and you'll find it on some Android phones as well. On the headphone side of things, AAC is available on Apple's own AirPods and Beats headphones, and is finding its way into non-Apple headphones as well.
- aptX and aptX HD: Owned by Qualcomm, these codecs use more efficient compression to provide higher fidelity audio than SBC. You'll find them codecs in quite a few Android phones. These formats also aim to lower latency, reducing the audio delay that can cause lip sync problems when you're watching videos and playing games. If you want the lowest latency possible, look for a headphone with aptX LL—the LL stands for "Low Latency."
- LDAC: Owned by Sony, LDAC allows for multiple audio qualities, and has potential for higher quality connections than any other Bluetooth codec. This codec now comes built into Android 8.0 Oreo, which means it's appearing on lots of new Android phones. It isn't as common in headphones, though, and you'll mostly find it in Sony models.