I am aware that articles are the modifiers, which introduce a noun/noun_phrase in a sentence, and by the rules of English grammar we should use an article before referring to a noun in a sentence.

However, I see that the above rule is not strictly followed. I have seen sentences where though a noun/noun_phrase is used in a sentence but an introductory article is not used.

Eg : Login to desktop and start the paint application [ Desktop is a noun, hence I expect either "Login to a desktop and ...." or "Login to the desktop at the corner and ....."]

So please help me understand, when can an article be omitted ?
Thanks in advance.


Question: Word to describe "a person who is only wishful to help others and cares little about themself"?
Answer: Magnanimous


  proceeding from or revealing generosity or nobility of mind, character, etc.: a magnanimous gesture of forgiveness.


A magnanimous person is someone whose generosity of spirit is large. A person willing to forgive an evil deed, demonstrating nobility and generosity of mind to his/her enemies.

Considerate


  Always thinking of what other people need or want and being careful
  not to upset them  He was always kind and considerate.