Most network protocols just provide channels between communicating entities and let application designers figure out what they want to use them for. For
example, 802.11 does not specify whether users should use their notebook computers for reading email, surfing the Web, or something else. In contrast, the
Bluetooth SIG specifies particular applications to be supported and provides different protocol stacks for each one. At the time of writing, there are 25 applications, which are called profiles. Unfortunately, this approach leads to a very large
amount of complexity. We will omit the complexity here but will briefly look at
the profiles to see more clearly what the Bluetooth SIG is trying to accomplish.