There are different categories of connectors.

Coordinators join equal parallel parts of grammar. Parallel parts of grammar are two or more of the same grammatical elements: finite verb phrases, noun phrases, adverb phrases, adverb phrases, or clauses. 

Subordinators join unequal clauses.                                     

Grammar doesn't stay together without glue!

Coordinators and subordinators are the glue that holds equal or unequal parallel parts of grammar together.

Click here for coordinators.                     

Click here for adverbial subordinators.  

Click here for adjectivial subordinators.                        

Click here for semicolon connectors.