Articles

Types of Articles

Articles everyone knows are articles:

I want a taco.
I ate the taco.

Articles few people know are articles:

I want this taco. ("this" may also be used as a pronoun)
I want that taco. ("that" may also be used as a pronoun or a conjunction)
I want these tacos. ("these" may also be used as a pronoun)
I want those tacos. ("those" may also be used as a pronoun)
I want some tacos. ("some" may also be used as a pronoun)
I will eat many tacos. ("many" may also be used as a pronoun)
I will eat any taco. ("any" may also be used as a pronoun)
I will not eat every taco.

Possessive articles (what most people call "possessive pronouns"):

I ate my tacos.
I also ate your tacos.
I will eat his tacos.
I will not eat her tacos because her tacos have cooties.
The dog ate its tacos.

(Note that "its" is not spelled with an apostrophe. Only the contraction of "it is" is spelled "it's." "Its" is a word just like "his" and "hers" which also are not spelled "hi's" and "her's.")

Proper possessive articles (what most people call "possessive proper nouns"):

Jack's tacos are cold.
Jill's tacos have cooties.

When to Use Articles

Use articles when speaking of specific objects:

My taco is tasty.
The key is locked in the car.
A taco is on his plate.

When generalizing, use an article only when the noun is singular:

A cat will not eat      tacos.
A cat will eat a mouse.
A cat will eat      mice.
     Cats will eat      mice.
     Tacos are tasty.
     People like to eat      tacos.

Do not use articles with proper nouns.
(Examples of proper nouns: "John" is a proper noun, but "person" is a normal noun. "Louisville" is a proper noun, but "city" is not.)

Your taco is from the store.
My taco is from      Taco Bell.

Do not use articles with pronouns.
(Pronouns are used in place of nouns which have already been mentioned. Examples of pronouns: John likes tacos. He has eaten many of them.

     These are the best tacos.
I like tacos.      They taste good.
     It is a good day to die.

Do use an article with proper nouns when the proper noun alone is not specific enough to identify the object.

I have a daughter named Jill and a son named Jack. Sam also has a son named Jack. All three go to the same school.      Jill and Sam's Jack are also in the same grade.

Do not use articles when referring to nouns which are measured rather than counted:

I have a glass of      water.
     Gasoline is expensive.

(This can sometimes be tricky since some measured quantites may also be counted, but are not being counted in the way they are used.)

Nathan sucks      dick.

(...and if that wasn't enough, even if the noun is measured rather than counted, if you meaure out portions of it, such that it can be counted, then it is no longer measured, even if there is only one such portion.)

I filled some bottles with      water.
I then loaded the water into my car.
I also filled the sink with      water.
The water in the sink is pointless.

Certain nouns which refer to places where people may be do not use articles, but only when speaking about a person being at that place for the reason one is usually at that place. There do not appear to be any specific rules, but instead it appears to be a matter of "people say it that way because people say it that way" since it appears to only occur with well-known places such as "work," "home," "school," etc.

Jack is at      school.
Sam went to the school to pick up his son.
Jill is at      home.
Jack went to Jill's home after school.
Joe was taken to      jail after he was arrested.
John went to the jail to visit Joe.

Where to Use Articles

Articles appear before nouns, and also before any adjectives that describe that noun. There may be only one article for each noun.

The taco is hot.
The green taco is hot.
The hot green taco is mine.
My hot green taco is not for sale.
Incorrect: Green the taco is hot. (The article must come before the adjective.)
Incorrect: Green my taco is hot. (The article must come before the adjective.)
Incorrect: The my taco is hot. (Only one article is allowed.)
Incorrect: That the taco is hot. (Only one article is allowed.)

What else?

...and now I'm tired of writing about this, so that's all!