A compound sentence is two simple sentences joined together. In other words, a compound sentence has two independent clauses.

Compound Sentence Patterns
In the following sentence patterns, IC = Independent Clause, c = FANBOYS and ca = conjunctive adverb.
Here are the three common compound sentences patterns:

1. IC, c IC The c represents the complete list of coordinating conjunctions. The first letter of each word can be arranged to spell the word FANBOYS. The seven words are for, and, nor, but, or, yet, so.
Examples: Walter didn’t want to argue in the staff meeting, so he said nothing.
Zhen likes his work in the accounting firm, but he doesn’t like working overtime.
2. IC; IC A semicolon can join two independent clauses when the two ideas are closely related.
Examples: I like winter sports; my wife prefers Florida.
The prime minister is promising a tax cut; I don’t believe him.
3. IC; ca, IC Examples: Yesterday a tornado touched down in Barrie; fortunately, no one was injured.
Lee has had fifteen job interviews; however, no one has offered him a position.

Here are some of the conjunctive adverbs that can be used in place of ca in this pattern:
To Introduce An Example
as you can see for one thing that is
for example in particular
for instance specifically

To Emphasize an Idea
above all in particular without doubt
indeed particularly
in fact unquestionably

To Add a Point
again in addition
also in the same way
besides likewise
furthermore moreover

To Show Cause and Effect
accordingly for that reason therefore
as a result it follows that thus
consequently then

To Show Contrast
after all nonetheless otherwise
however occasionally still
in contrast on the contrary unfortunately
nevertheless on the other hand

To Show Sequence
at first first (never firstly) secondly, thirdly...
at last in the first place to begin with
at the end next
finally second, third...

To Restate an Idea
in other words in short that is

To Show Time
afterward immediately presently
at present in the future previously
at the same time in the past shortly
at this time lately simultaneously
earlier meanwhile subsequently
eventually nowadays tomorrow
formerly once ultimately

To Show Similarity
in like manner in the same way similarly

To Conclude
accordingly consequently lastly
all together finally therefore
as a result in conclusion thus