The basic unit of speech and writing is the sentence. A sentence is a series of words (or combination of words) that form a complete thought.
For example:
Every complete sentence contains two parts: a subject and a predicate. The subject is what (or whom) the sentence is about, while the predicate tells something about the subject.
The subject is the person, thing or topic which the sentence deals with. When we speak or write, we speak or write about something, The subject is what is being spoken about. For example:
The predicate is all of the sentence except the subject. The predicate is what we say about the subject. For example:
A phrase is a group of words that does not contain the main verb. A clause is a group of grammatically related words that does contain a main verb.