Parts of a Simple Declarative Sentence

Traditional classification:

Source: https://ieltsband7.com/ielts-vocabulary/grammar/subject-and-predicate/

In terms of definition-:

SUBJECT

The part which names the person or the thing we are talking about in the sentence.

PREDICATE

What we say about the subject is called the predicate.

The predicate can be subdivided into Auxiliary (Operator) and predication

Alternative classification:

Source: https://ieltsband7.com/ielts-vocabulary/grammar/subject-and-predicate/