Coordinate Conjunction

 Co-ordinate conjunctions join similar words, phrases or clauses to each other (i.e., to join an adjective to an adjective or a noun to a noun).  The most common co-ordinate conjunctions are: and, but, or, for, nor, so and yet.

The conjunctions and, but and or are the most common by far.

Examples:
            The waiters served sandwiches and cokes. (joins two nouns)
He is a small but aggressive cat. (joins two adjectives)
The manager or his secretary will be with you in a minute. (joins two nouns)
He typed the letter quickly but accurately. (joins two adverbs)

In the examples above, the conjunctions all join words.  As a general rule, when a conjunction joins two words, there is no need to precede it with a comma.  However, when it joins two clauses, it is usual to place a comma before the conjunction.

Examples:
The applicant must be able to sing and dance. (no comma)
The applicant must be able to sing, and she must be able to dance. (joins two clauses – comma required)

However, if the independent clauses are short and well-balanced, a comma is not really essential:

She is kind so she helps people.

When “and” is used with the last word of a list, a comma is optional:

He drinks beer, whisky, wine, and rum. // He drinks beer, whisky, wine and rum.

The 7 coordinating conjunctions are short, simple words. They have only two or three letters. There’s an easy way to remember them – their initials spell: