1. Concept:
1.1. The indefinite articles are words that precede the nouns, indicating its gender and number
2. Graphic Example:
2.1. Video
2.1.1. "a" and "an"
3. Use
3.1. Functions:
3.1.1. Is used to and even to designate persons and things
3.1.1.1. Example: -a man -an umbrella
3.1.2. Is used to and even in front of professions (in this case, unlike the spanish in that the profession does not require precede article a or a)
3.1.2.1. Example: -I am an Engineer -He is a Painter
3.1.3. Serves to designate an individual or object as representative of a class
3.1.3.1. Example: -A car is better than a motorbike
3.1.4. Has a distributive use
3.1.4.1. Example: -Twice a day
3.1.5. In front of words which indicate measures, price, etc. when they are followed in Spanish by the preposition by or behind adverbs of quantity as such, half, etc.
3.1.5.1. Example: -Twenty miles an hour -Such a thing
4. Rules
4.1. Rule 1
4.1.1. Is unchanged in gender and number. This means that serves the same way for both male and female for the
4.1.1.1. Example: -A boy -A girl
4.2. Rule 2
4.2.1. Lacks the plural. In order to convey the meaning of a few, some uses the adjective "some"
4.3. Rule 3
4.3.1. Is used in front of words that begin with consonant, by h aspirated, or by u, EU, ew when pronounced /ju:/, and in front of words that begin with or when you pronounce U
4.3.1.1. Example: -A chair -A Useful Think
4.4. Rule 4
4.4.1. It is used an in front of words that begin with a vowel or by h not pronounced
4.4.1.1. Example: -an Orange -an Heir