Comma

 - the mark ( , ) used to separate the items in a list or to show where there is a slight pause in a sentence

The use of punctuation was not seen until after the invention of printing.

The importance of punctuation was noted in various sayings by children such as:                                                                           

Charles the First walked and talked

Half an hour after his head was cut off.                 

With a semi-colon and a comma added it reads:

Charles the First walked and talked;

Half an hour after, his head was cut off.

1. When we have two independent ideas (a predicate and a subject - as two main parts of a sentence ), we put a comma before FANBOYS – for, as, nor, but, or, yet, so.                                                                                                         
   Example: I met Harry, we went for a swim together, and afterwards Harry went home.  I like your son, I might even love him, but he is not a very good soccer player.
    

2. When we have three or more items with or without conjunctions AND \ OR.                                                           Example: For dinner I had soup, fish, chicken, dessert, and coffee.                                                                                                

   The last one is called the Oxford Comma. It is also known as the Serial Comma or the Harvard Comma. The Oxford comma is much more widespread in American English than British English. Many people prefer not to use this style and will omit the final comma. We call this the Oxford comma because it is the standard method taught at Oxford University.
    

3. When the condition is on the first place in a conditional sentence, we put a comma after it.                                     Example: Unless you are going, I won't go.

4. When we have extra information in a sentence.                                                                                                        
   Example: Lucy, who is a tall woman,  climbed the tree. His brother, I have forgotten to mention, was a doctor.
    

5. Direct speech.             
   Example: Не says, "She will come in the evening."
    

6. Linking words, word combinations.       
   Example: Naturally, that is not the whole story. To put it mildly, he has been impolite.
    

7. When you address to a person.
   Example: Waiter, I’d like the menu, please. But mother, there is no one here.
    

8. Introductory phrase (three or more words).
   Example: After visiting her, we intend to go there.
    

9. Expressing contrast.
   Example: She was intelligent, not especially practical.
    

   A comma splice

A comma splice is the use of a comma to join two independent clauses. 

Example:            - Black bears are beautiful; they have shiny coats. \\ or Black bears are beautiful. They have shiny coats. \\ or Black bears are beautiful (no comma)  because\since\if they have shiny coats.

• I love watching (no comma) I hate listening. \I love watching, but I hate listening.

                                                          

  Comma (short version)

• When we have two independent ideas.

• When we have three or more items.

• When the condition is on the first place.

• When we have extra information in a sentence.

• Direct speech.            

• Linking words, word combinations.

• When you address to a person.

• Introductory phrase (three or more words).

• Expressing contrast.