Sentence structure can be classified based on the number and type of clauses. A simple sentence contains one independent clause, while a compound sentence contains two or more independent clauses joined with a conjunction. A complex sentence has one or more dependent clauses in addition to at least one independent clause. Sentences can also be a combination of complex and compound, containing both dependent clauses and multiple independent clauses.

1. Sentence clause structure
In grammar, clause structure refers to the classification of
sentences based on the number and kind of clauses in
their syntactic structure. Such division is an element of
traditional grammar.
A simple sentence consists of only one clause. A
compound sentence consists of two or more independent
clauses. A complex sentence has at least one independent
clause plus at least one dependent clause.[1]
A set of words
with no independent clause may be an incomplete
sentence, also called a sentence fragment.
A sentence consisting of one or more dependent clauses
plus two or more independent clauses may be called a
complex-compound sentence or compound-complex
sentence.[2][unreliable source?]
Sentence 1 is an example of a simple sentence. Sentence 2
is compound, while sentence 3 is complex. Sentence 4 is
compound-complex (also known as complex-compound).
Example 5 is a sentence fragment.
1.I like pumpkin pie.
2.I don't know how to bake, so I buy my sweets.
3.I enjoyed the apple pie that you bought for me.
4.The dog lived in the garden, but the cat, who was
smarter, lived inside the house.
5.What a silly dog.

2. The simple sentence in example 1 contains one clause.
Example two has two clauses (I don't know how to bake
and I buy my sweets), combined into a single sentence
with the coordinating conjunction so. In example 3, I
enjoyed the apple pie is an independent clause, and that
you bought for me is a dependent clause; the sentence is
thus complex. In sentence 4, The dog lived in the garden
and the cat lived inside the house are both independent
clauses; which was smarter is a dependent clause.
Example 5 features a noun phrase but no verb. It is not a
grammatically complete clause.
Contents
 1 Simple sentences
 2 Compound sentences
 3 Complex and complex-compound sentences
 4 Incomplete sentence
 5 References
 6 External links
Simple sentences
A simple sentence structure contains one independent
clause and no dependent clauses.[3]
 I run.
This simple sentence has one independent clause which
contains one subject, I, and one predicate, run.

3.  The girl ran into her bedroom.
This simple sentence has one independent clause which
contains one subject, girl, and one predicate, ran into her
bedroom. The predicate is a verb phrase that consists of
more than one word.
 In the backyard, the dog barked and howled at the
cat.
This simple sentence has one independent clause which
contains one subject, dog, and one predicate, barked and
howled at the cat. This predicate has two verbs, known as
a compound predicate: barked and howled. This
compound verb should not be confused with a compound
sentence. In the backyard and at the cat are prepositional
phrases.
Compound sentences
A compound sentence is composed of at least two
independent clauses. It does not require a dependent
clause. The clauses are joined by a coordinating
conjunction (with or without a comma), a semicolon that
functions as a conjunction, a colon instead of a semicolon
between two sentences when the second sentence explains
or illustrates the first sentence and no coordinating
conjunction is being used to connect the sentences, or a
conjunctive adverb preceded by a semicolon. A
conjunction can be used to make a compound sentence.

4. Conjunctions are words such as for, and, nor, but, or, yet,
and so (the first letters of which spell "fanboys"). The use
of a comma to separate two independent clauses without
the addition of an appropriate conjunction is called a
comma splice and is generally considered an error (when
used in the English language).[3]
Complex and complex-compound sentences
Main article: Dependent clause
A complex sentence has one or more dependent clauses
(also called subordinate clauses). Since a dependent
clause cannot stand on its own as a sentence, complex
sentences must also have at least one independent clause.
A sentence with two or more independent clauses plus
one or more dependent clauses is called compound-
complex or complex-compound.
In addition to a subject and a verb, dependent clauses
contain a subordinating conjunction or similar word.
There are a large number of subordinating conjunctions in
English. Some of these give the clause an adverbial
function, specifying time, place, or manner. Such clauses
are called adverbial clauses.
 When I stepped out into the bright sunlight, from the
darkness of the movie house, I had only two things
on my mind. (S. E. Hinton, The Outsiders)

5. This complex sentence contains an adverbial clause,
When I stepped out into the bright sunlight from the
darkness of the movie house. The adverbial clause
describes when the action of the main clause, I had only
two things on my mind, took place.
A relative clause is a dependent clause that modifies a
noun or noun phrase in the independent clause. In other
words, the relative clause functions similar to an
adjective.
 Let him who has been deceived complain. (Miguel de
Cervantes, Don Quixote)
 You, who have never known your family, see them
standing around you. (J.K. Rowling, Harry Potter and
the Sorcerer's Stone)
In the first example, the restrictive relative clause who has
been deceived specifies or defines the meaning of him in
the independent clause, Let him complain. In the second
example, the non-restrictive relative clause who have
never known your family describes you in the
independent clause, You see them standing around you.
A noun clause is a dependent clause that functions like a
noun. A noun clause may function as the subject of a
clause, or as a predicate nominative or an object.

6.  What she had realised was that love was that moment
when your heart was about to burst. (Stieg Larsson,
The Girl with the Dragon Tattoo)
In this sentence the independent clause contains two noun
clauses. The noun clause What she had realized serves as
the subject of the verb was, and that love was that
moment serves as complement. The sentence also
contains an adverbial clause, when your heart was about
to burst.
Incomplete sentence
An incomplete sentence, or sentence fragment, is a set of
words which does not form a complete sentence, either
because it does not express a complete thought[1]
or
because it lacks some obligatory grammatical element,
such as a subject or a verb.[4]
A dependent clause without
an independent clause is one example of an incomplete
sentence.
Some prescriptive grammars[5]
consider sentences starting
with a conjunction such as but or and as incomplete
sentences, but this style prescription has "no historical or
grammatical foundation".[6]
Computer grammar checkers
often highlight incomplete sentences. If the context is
clear from the rest of the p