Native speakers of English rarely give articles (a, an, and the) a second thought. But for non-native speakers of English, they can be the trickiest item in the language. These tips will help you select the right article for the right situation.
A. refers to something previously mentioned.
"The problems you identified in today's meeting..."
B. stands for all other items of its type.
"The fax machine has changed the way we do business."
"Bell Labs pioneered use of the transistor."
C. is identified by a special adjective.
(1) A superlative: the biggest IPO, the most important consequence.
(2) A particular (ordinal) number: the second phase, the twentieth anniversary.
(3) A proper name [usually]: The United States [but Canada], the Atlantic Ocean [but Raritan Creek]; the quality control team; the assessment project.
D. refers to a time or place treated as one collective unit: the Sixties, the earth, the sun, the teens.
E. is followed by modifiers, especially relative clauses or "of" phrases: the supervisor who wrote the memo, the outcome of the break-up, the employee in charge of scheduling.
F. refers to knowledge the writer/speaker and audience share: the recent field test at Indian Hill, the MERLIN project.
G. refers to a particular object, even if the reader doesn't yet know it's particular: Install the modem controller in the slot provided.
A. is readily found in plurals: memos, supervisors, tasks, days off.
B. occurs readily with numbers: 5 RFPs, 238 factories, 8450 workers.
C. occurs with adjectives that suggest numbers: few drawbacks, most 800 numbers, several locations.
A. refer to physical masses without distinct form or shape: water, ROM, sand, fat, oil, neon.
B. refer to an abstract concept: gravity, information, justice, satisfaction, apartheid.
C. refer to ongoing processes: respiration, growth, pollution, communication.
D. refer to a field of study or endeavor: engineering, optics, materials science, baseball.
Exercise. Here is an excerpt from William F. Zachmann's column, "The Real-world Problems with UNIX," which appeared in PC Magazine (6/12/90, pp. 89-90). Justify the use of a, an, or the, or the omission of an article, in front of each noun, as underlined.
...My last column...identified some of the obstacles standing in the way of OS2's acceptance....Clearly, if Microsoft and IBM fail to establish OS/2 as the heir to DOS for office systems, UNIX will be the primary beneficiary. Worsening prospects for OS/2 translate into better prospects for UNIX....As an operating system for office desktop PCs, UNIX has problems of its own. First, UNIX is far from being the single standard that it is sometimes made out to be. Granted, considerable progress has been made toward standardization over the last ten years. Nevertheless, UNIX remains a more heterogenous collection of implementations than a user might expect.
•Do not use an article with common nouns used as terms of address (and usually capitalized): Thank you, Dad; The report is finished now, Professor.
•Do not use an article with an acronym that you pronounce as a word: NATO, UNIX, DOS.
--when using a proper noun to indicate characteristics of the named person: He's a Rambo in negotiations.
--to mean "a certain person whose name is": A Mr. Chang called this morning.
--For surnames in the plural: The Martinezes are moving.
--To distinguish between people with the same name: The Michael Jackson in Accounting isn't the singer Michael Jackson.
--When the article is part of an accepted geographical name (there's no rhyme or reason, just custom, to these):
the Philippines the USSR the United States
the Red Sea the Atlantic or Pacific Ocean
the Mississippi the Great Lakes the Alps--When the article is part of an accepted proper name, such as a ship, newspaper, desert, group, hotel, etc.: The Hilton, the New York Times, the Titanic, the Sahara, the Beatles, the United Nations, the Super Bowl
--With most acronyms that have separately pronounced letters: the U.N., the U.S.A., the F.B.I., the I.N.S. Exceptions include IBM, AT&T, MIT, UCLA, RCA, GE.