We use the following types of sentences: simple, compound, complex, compound-complex and fragments.
Simple sentences have one independent clause.
Monday is the deadline for the project.
Simple sentences will always be part of your writing and they work particularly well at the beginning and end of paragraphs. However, too many simple sentences in a row look and sound simplistic.
Compound sentences have two or more independent clauses joined by a coordinating conjunction. The coordinating conjunctions can be summarised by the acronym FANBOYS. They are for, and, nor, but, or, yet, so.
Use a comma to separate two independent clauses unless the clauses are short and the meaning is clear without a comma.
Monday was a rainy day, and the workers stayed home. (comma = correct)
Monday was a rainy day and the workers stayed home. (no comma is OK because the meaning is clear without it)
Complex sentences have an independent clause and one or more dependent clauses. They are useful for commenting on your main idea.
Although it rained on Monday, the work on the roof continued.
Dependent clause: Although it rained on Monday
Independent clause: the work on the roof continued.
Compound-complex sentences have more than one independent clause and at least one dependent clause. They tend to become cumbersome and are often better tightened and split into two sentences.
Before: The team met in the morning to discuss the project, which was running behind schedule, and then adjourned for lunch, which was provided in the boardroom.
Rewritten: The team met in the morning to discuss the project, which was running behind schedule. Then lunch was provided in the boardroom.
A sentence fragment is an incomplete sentence. Fragments have their place in informal writing and in tables that are in note form.