There are a lot of rules for articles:

1. Don’t put an article in front of the name of a place.

• Correct: Minneapolis is a great city.
• Not correct: The Minneapolis
  is a great city.

But it is correct to use the name of a place as an adjective:

• The Minneapolis skyline is
  beautiful at night.
• The Chicago River is painted green on St. Patrick’s Day.

2. Indefinite amounts or general
qualities don’t take an article.

• Pennies are made of copper.
• The copper
  in this penny is turning brown. (This is a specific amount.)
• Water is good for you.
• The water
  in this glass tastes bad. (This is
  a specific amount.)
• Honesty is the best policy.

3. Don’t use an article with possessive nouns
or pronouns.

This is the Mr. Etesami’s website.

4. The definite article can be used with singular or plural nouns:

• The apples taste great. (plural)
• The apple tastes great. (singular)
• Apples taste great. (general category)
• The water is clean. (noncount noun)
• Water is necessary for life.