The purpose of the predicate in the field of grammer:

Sentence structure is unique in all cultures. It can be easy to tell where a person comes from by listening to their sentence structure when they speak. Language can be defined, in some sense, on how a majority of people interpret people, places and things verbally. In sentence structure you have a subject that has to form an idea and also modify a subject. Lets use an example: Jody is running for office.  "Jody" is the subject "is running for office" is the predicate. There are many types of predicate structures. In this sentence it would be safe to say that this is a traditional or common structure. The purpose of the predicate is to form an idea or modify the subject of a sentence.