Comma (n): A mark of punctuation used to indicate a division in a sentence, as in setting off a word, phrase, or clause, to separate items in a list, to mark off thousands in numerals, to separate types or levels of information in bibliographic and other data.

Consider the lowly comma.
If you regard it as a mere flyspeck with a tail, that may account for the some capricious uses (and non-uses) of it that appear from time to time.

• Example 1: “The luncheon was in honor of three new council representatives from Australia, Cuba, and Yugoslavia…”

Without a comma after “representatives” the meaning is that three new representatives are replacing three old ones.

A comma (perhaps preferably a dash) would have brought out the correct meaning, that representatives of the three countries were new to the council.

• Example 2: “… as the lips and skin of the mask are in natural colors, the inventor says, a very lifelike illusion is created.”

Insert a comma after “says” to set off a parenthetical phrase.

Put commas within closing quotation marks.

• “I may forget your name, but I always remember a face,” he said.
  “John talks a good game,” says Steve, “but when it comes to taking action, Robert is much better.”

Use commas to separate elements in a series, and DO put a comma before the conjunction in a simple series of three or more items.

• The flag is red, white, and blue.
• He would nominate Tom, Dick, or Harry.

USING COMMAS WITH THE WORD “HOWEVER”:

Using “however” to begin a sentence:
If “however” is used to begin a sentence, it must be followed by a comma, and what appears after the comma must be a complete sentence.

• However, there was no need to repeat the data entry.

Using “however” as an aside:
“However” can be used to interrupt a sentence. Use a comma before and a comma after “however” when you use it in this way.

• It is, however, extremely difficult to identify all the relevant variables.