Sentence

Sentence is a group of word that have one concept/idea. There are few characteristics of a group of words to be called a sentence, that is:
First, the entire words form one concept. In other words, the sentence doesn't have more than one meaning. For example: Altria catches a butterfly yesterday. This sentence have no other meaning beside what we get from reading.
Second, a sentence at least consist of subject and predicate. This type of sentence is the simplest sentence, and named 'simple sentence'.
For example: The Hallway   is clean
                              S                P

The sentence above is an example for simple sentence. Even without an object, reader should be able to grasp the meaning behind the sentence.
Third, types of sentence. There are four types of sentence, as the following:
• Declarative, stating something.
 Example: Martha is training her dragon.
 • Interrogative, asking about something in form of 5W+1H.
 Example: Where is Elizabeth?
• Imperative, giving command or requesting something.
 Example: Please leave the command room now!
• Exclamarative, giving strong emotion.
Example: Today's weather is perfect.

 Beside simple sentence, there are three more kinds of sentence.
 First, compound sentence. In compound sentence, there are little thing called conjunction. Conjunction connect the first half (called a clause) of the sentence with the rest.
 Example: Mash is catching a bug,    and    Altria is catching a butterfly.
                         first clause              conj.           second clause

 Next, there are complex sentence. In complex sentence there are a clause called dependent clause, meaning the clause can not stand alone, a subordinator and independent clause. So if the subordinator comes first followed by dependent clause, there must be a comma separating two clauses.
Example: Because     she failed the test,    Chacha is crying.
          Subordinators    dependent c.           independent c.

 Last but not least, there are Compound-complex sentence. This type is combination between compound sentence and complex sentence.
Example: Because   it is raining,  Emma can't go home    since   she didn't brings her umbrella
                  Sub.      depend.c.                                       conj.