Transition to American Academic English

Articles

Almost every noun (name of something) in formal English has a determiner (a word which tells us what sort of thing it is). Some determiners carry a lot of information ("blue" or "my"), while others carry relatively little information ("a" "an" "the"). These little words, the articles ("a" "an" "the"), cause trouble for second-language speakers.

• A bird in the hand is worth two in the bush.
• The blue car squeezed into my parking space.

An exception to this rule is nouns that refer to whole categories. They do not usually have determiners:

• Science is organized knowledge. Wisdom is organized life.
  (We would not say, "The science" or "A wisdom" in these sentences.)

Definite and indefinite articles

These little words do not carry much meaning, but they do carry some.

• Definite article: The speaker is thinking of a specific example.
  ("I would like the roast beef sandwich." Perhaps the speaker is looking at an item on a menu or pointing to a sandwich at a food counter.)
• Indefinite article: The speaker is thinking in general categories. Yes, the indefinite article is required in most situations.
  ("I would like a roast beef sandwich." The speaker is imagining a sandwich; perhaps the speaker has not even arrived at the restaurant.)

a, an, and

Even speakers whose first language is English sometimes have trouble with these.

• and is the word that joins two things together: "I would like ham and eggs."
  • Yes, informal speakers often drop that last consonant and say, "I would like ham an eggs," but that is an informal speech pattern, not formal written English.
• a is the indefinite article which goes before a noun which starts with a consonant sound: "I would like a cup of coffee."
• an is the indefinite article which goes before a noun which starts with a vowel sound: "I would like an apple."
  • Some informal spoken versions of English prefer to solve the "vowel crash" with a glottal stop and would say "I would like a ¿ apple."
  • Using "a" before a vowel is really a grammar error; this is the reason Microsoft Word flags it with a blue squiggle underline.