1. Writing Complex Sentences

2. #1: Simple Sentence A simple sentence has one subject and one verb
I like to study grammar.
A simple sentence is also called an independent clause.
An independent clause ends with a period or semicolon.
As the name suggests, independent clauses are independent—they can stand alone. In other words, independent clauses can be complete sentences. They contain a subject and a verb and express a complete thought. With the right punctuation, they can also combine with dependent clauses, phrases, and other independent clauses to create complex and compound sentences.
Examples of independent clauses:
Jason is tired. Lolita had coffee with breakfast. Studying in groups helps college students earn better grades.  The feminist movement in the United States is defined as occurring in three distinct waves. Most of the action of the novel takes place in New York.
Dependent Clauses
When it comes to dependent clauses, the name says it all: dependent clauses depend on something else, usually independent clauses, to form complete sentences.  They cannot stand alone. A dependent clause contains a subject and a verb, but does not express a complete thought. The most common types of dependent clauses, adverbial clauses and adjective (also called relative) clauses, must be combined with independent clauses in order to avoid creating sentence fragments. (The third type of dependent clause is called a noun clause.)
Because adverbial clauses cause some of the most repeated fragment errors in college writing, this handout focuses on them and their dependency upon independent clauses.

3. I love you. Simple sentence
One subject
I love you.
One verb
Independent Clauses
The independent clause is the dominant, main clause of the sentence.
When only one clause is contained in a sentence, it is known as an independent clause.  Independent clauses can be combined in the same sentence as dependent clauses. If the sentence were broken apart, the independent clause would still make sense, although the dependent clause would be merely a sentence fragment.
Independent clause: only one subject and one verb

4. #2: Compound Sentence
A compound sentence is made up of two or more simple sentences joined by one of the following:
A comma and one of the FANBOYS
I like to study grammar, and I love this class.
A semicolon
I like to study grammar; I love this class.
A semicolon and a transitional
I like to study grammar; therefore, I love this class.
Experienced writers use a variety of sentences to make their writing interesting and lively. Too many simple sentences, for example, will sound choppy and immature while too many long sentences will be difficult to read and hard to understand. 
COMPOUND SENTENCE
A compound sentence contains two independent clauses joined by a coordinator. The coordinators are as follows: for, and, nor, but, or, yet, so. (Helpful hint: The first letter of each of the coordinators spells FANBOYS.) Except for very short sentences, coordinators are always preceded by a comma.

5. I love you, and you love me.
Compound sentence
Independent clause
I love you, and you love me.
Independent clause
Each sentence contains two independent clauses, and they are joined by a coordinator with a comma preceding it.
Two independent clauses joined together

6. #3: Complex Sentence
A complex sentence is a simple sentence (independent clause) to which a part of a sentence (dependent clause) has been added.
Because I like to study grammar, I love this class.
I love this class because I like to study grammar.
A complex sentence has an independent clause joined by one or more dependent clauses. A complex sentence always has a subordinator such as because, since, after, although, or when or a relative pronoun such as that, who, or which.

7. Because you love me, I love you.
Complex sentence
Dependent clause
Because you love me, I love you.
Independent clause
Sentences containing adjective clauses (or dependent clauses) are also complex because they contain an independent clause and a dependent clause. 
A dependent clause joined to an independent clause. (The dependent clause needs the rest of the sentence for support.)

8. Fragment! Because you love me. Dependent clause
A dependent clause contains a subject and verb. It begins with a subordinating conjunction, and thus it does not express a completed thought. A dependent clause is also called a subordinate clause.
Dependent clauses, like babies, cannot stand alone.
Dependent clauses only serve to modify (describe, or provide information about) independent clauses. 
Unlike independent clauses, dependent clauses cannot exist by themselves.  Dependent clauses do contain a subject and a verb, but they don’t form a complete thought.  Alone, they are only sentence fragments - and form serious grammatical errors.

9. A Tip on Punctuation
Since dependent clauses are only part of a sentence, you can never connect them to another sentence with a semicolon. Semicolons are only used between two independent clauses.
I have loved you for years ; although I never admitted it.
I have loved you for years, although I never admitted it.
This is a common mistake among middle school students. Semicolons are only used to connect two independent clauses.
No! OK

10. Common Subordinating (Dependent) Conjunctions
after
even if
now that
that
where
although
even though
once
though
whereas as if
rather than
unless
wherever
as if
whenever
since
until
whether
because
in order
so that
when
which
before
than
in case
while

11. #4: Compound/Complex Sentence
A compound/complex sentence is the last and most complicated type of sentence.
It contains at least one dependent clause and at least two independent clauses.

12. Compound complex sentence
Dependent clause
Because we are a family, I love you, and you love me.
2 independent clauses
A compound-complex sentence is made from two independent clauses and one or more dependent clauses.
Some examples:
1. Although I like to go camping, I haven't had the time to go lately, and I haven't found anyone to go with.
independent clause: "I haven't had the time to go lately"
independent clause: "I haven't found anyone to go with"
dependent clause: "Although I like to go camping... "
Even though he prefers to eat with a fork, he chooses to use chopsticks in Chinese restaurants; however, they aren't easy to use.
independent clause: he chooses to use chopsticks in Chinese restaurants
independent clause: they aren't easy to use.
dependent clause: Even though he prefers to eat with a fork
A dependent clause added to two or more independent clauses

13. Since every sentence in English fits into one of these four categories,
Simple
Compound
Complex
Compound/
complex
A common weakness in writing is the lack of varied sentences. Becoming aware of three general types of sentences--simple, compound, and complex--can help you vary the sentences in your writing.

14. CONGRATULATIONS! YOU NOW KNOW EVERYTHING YOU NEED TO KNOW
To write anything you want to write
Any way you want to write it
And still get the punctuation right each time!
Telling the difference between independent and dependent clauses equips you with a powerful editorial tool, so you can avoid making such classic, glaring grammar mistakes like run-on sentences and sentence fragments
CONGRATULATIONS!