Grammatically Correct: The writer's essential guide to punctuation ...

Basic Sentence Structure
In order to understand the logic behind some rules of punctuation,
particularly those pertaining to the comma and the semicolon, it is
necessary to understand the basic components of a sentence. Read
this section before turning to the review of the comma, because
that section makes multiple references to the terms defined here.
SUBJECT, PREDICATE, CLAUSE
A grammatically complete sentence includes, at a minimum, two
things: a subject and a predicate. The subject is any sort of entitya
person, a place, an object, an abstract concept, a pronoun that
refers to some entity identified elsewhere or an action functioning
as a noun. The predicate gives some information about the subject,
either describing it or identifying an action that it performs or that
is performed upon it (its "predicament"). If any object is affected
by the subject's actions, that object is part of the predicate as well.
Together, a subject and a predicate constitute a clause. A sentence
may contain more than one clause.
In the examples below, the subject and predicate are separated
by a slash.
• Usually, the subject precedes the predicate.
Fish/swim.
Subject is a concrete noun; predicate identifies an action performed
by the subject.
The silence/was shattered.
Subject is an abstract noun; predicate identifies something done to
the subject.
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