The ART Area works on the application layer and related protocols:
These are protocols that enable interactive human-to-human communication (see RFC 3550).
Groups in this category are working on things such as real-time web communications, teleconferencing, emergency services communication, internet telephony, and instant messaging.
These are the protocols we've generally thought of in relation to the application layer.
They include such things as email, calendaring, directory services, provisioning and access protocols related to DNS and IP and support for constrained environments.
These are designed to be used with a variety of more specific applications.
They include compression, codecs, internationalization; JSON, XML, and CBOR; media types; URNs; and URI schemes.