Someone told me that when you're counting words in an essay, words such as "a", "the", "and", "to" do not count. Is this statement correct?

No, that statement isn't true. In a 500-word essay, "little words" like articles, conjunctions, and prepositions will typically make up about 20% of the total in the document—that's a huge amount to ignore! We've never heard of anyone counting words by leaving the little ones out.

What we have heard before are questions about how some kinds of words—like contractions, hyphenated words, and numbers—are counted. Here's some more information about these special cases.

Contractions: Contractions (such as "don't" and "I'll") are generally considered to be one word.

Hyphenated words: There's varying opinions about these. Some people would say "first-class" counts as one word, others say two. To be on the safe side, if you're short on words count them as one and if you're running over count them as two. People rarely consider longer hyphenated phrases, such as "devil-may-care," to be simply one word. If each part of a hyphenated word isn't a full word itself (as in "de-emphasize"), you should count the hyphenated word as one.

Numbers: Numbers expressed as numerals (1990, 19,582, 28) count as one word.

Abbreviations and acronyms: Abbreviations, like S.H.S. for "Smithville High School," are usually counted as if they were written out. However, common acronyms (like IBM and NAACP) that are used more often than the full name of the organization are often counted as one word.

Initials: Initials are counted as a full word. "George W. Bush" would be considered three words.

Titles: The title of your essay usually won't count towards the word limit.

An admissions office will probably use one of a few methods to count words. If they want an exact count, they may go through the document and count each word, either by hand or more likely by using a computer program. Or, they may count the number of words in a part of the document and use that information to estimate the total. For example, they might count the words in the first five lines, divide by five to figure out an average number of words per line, and then multiply the words per line by the total number of lines in the essay. Finally, an admissions officer may simply eyeball a document to make sure that it's the expected length (taking into account smaller fonts or margins). There are about 600-700 words in a single-spaced page written in 12-point font, so a 500 word essay should be shorter than a page.

Admissions officers generally don't have time to count words in the thousands of essays they read, so they're most likely to use the last method, if they care about the length of an essay at all. However, be wary of using that fact as an invitation to go over the word limit—there are some real sticklers out there. While a college would be unlikely to reject you simply because you used too many words, it makes a bad impression on some people and may indicate that you don't follow directions, aren't detail-oriented, or aren't respecting the admissions officer's time.

Related links:

Finding and Removing Unnecessary Words
How long is too long?