Commas and compound sentences

A compound sentence is a sentence that contains at least two independent clauses joined by a coordinating conjunction (for, and, nor, but, or, yet, so).

Commas are used in compound sentences to separate the independent clauses, especially when they are joined by a coordinating conjunction.

The correct sentence is: 'I wanted to go for a walk, but it started to rain.'

A comma should be used after an introductory phrase or clause that precedes the main clause.

After dinner, we went for a walk.

A coordinating conjunction connects two independent clauses, indicating a relationship between them.

For, And, Nor, But, Or, Yet, So (FANBOYS).

You should use a comma before a coordinating conjunction when it connects two independent clauses.

An independent clause is a group of words that contains a subject and a verb and expresses a complete thought.

A dependent clause is a group of words that contains a subject and a verb but does not express a complete thought.