what is the reasons of creating AAC profiles?

[freedom999]

can someone declare for me that every AOT(profile) of AAC is created for what?
like: HE,LC,Main,Ltp, etc

[Kurtnoise]

To make sure that some products work with other products and/or from other vendors.

[bond]

HE is not a profile

the different profiles use different encoding tools afaik, where LC is the most popular one (and was also already available in mpeg-2)

other profiles added in mpeg-4 add things like better quality for harder decodeability aso for example