Bluetooth Advanced Audio Distribution Profile (A2DP)

The Advanced Audio Distribution Profile is a Bluetooth profile that allows for the wireless transmission of stereo audio from an A2DP source (typically a phone or computer) to an A2DP receiver (a set of Bluetooth headphones or stereo system). Such devices typically also support the AVRCP profile as well in order to allow for track selection and such. A common misconception is that A2DP support is available on all Bluetooth 2.0 devices, which is not the case, and that A2DP is only available on Bluetooth 2.0 devices, which is also not true. A2DP support can exist in older versions of Bluetooth, it just was not commonly supported.

^{mobileburn.com: What is "A2DP"?}

It [A2DP] includes mandatory support for the low-complexity SBC codec (not to be confused with Bluetooth's voice-signal codecs such as CVSDM), and supports optionally: MPEG-1, MPEG-2, MPEG-4, AAC, and ATRAC, and is extensible to support manufacturer-defined codecs, such as apt-X. [...] It includes mandatory support for the low-complexity SBC codec [...] and supports optionally: MPEG-1, MPEG-2, MPEG-4, AAC, and ATRAC, and is extensible to support manufacturer-defined codecs, such as apt-X.

^{Wikipedia: Bluetooth profiles - A2DP}