Complex sentence: Grounding in communication (or common ground) is a concept proposed by Herbert H. Clark and Susan E. Brennan It is comprised of the collection of "mutual knowledge, mutual beliefs, and mutual assumptions" that are essential for communication between two people.
Split into simpler sentences: Grounding in communication (or common ground) is a concept proposed by Herbert H. Clark and Susan E. Brennan. It comprises the collection of "mutual knowledge, mutual beliefs, and mutual assumptions" that is essential for communication between two people.