1. A comma fault occurs when two independent clauses have been joined together with a comma. Divide into two separate sentences or join the clauses with a coordinating conjunction or with a semicolon.

INCORRECT
Dictionaries are word museums, the best ones
contain comprehensive collections.

CORRECT
Dictionaries are word museums, and the best ones
contain comprehensive collections.

¿
CORRECT
Dictionaries are word museums; the best ones
contain comprehensive collections.

2. When clauses of a compound sentence are short and closely related, they may be correctly joined with a comma.

(Warning: Use with extreme caution.)
CORRECT
Will I be pretty, will I be rich?
I came, I saw, I conquered.
Don't hurry, don't worry.