Homophones, or words that sound the same but have different meanings and spellings, are some of the more difficult words for English language learners. They can also cause native English speakers to stumble, producing such writing atrocities as "righting a letter," or inquiring after a friend's "sun and daughter." Some of the most mistaken homophones in the English language are to, two, and too — an especially especially confusing set of homophones, as there are three words that can become confused.
Two is the most simple of the three words. It generally just refers to the number, the answer to one plus one, also written as 2 or II. That is the easy definition. If you want to get more complicated, two can also mean a group, or set, of things or people: "Which children are yours?" "Oh, those two over there." A two can refer to a domino or a playing card with that number or value on it. Less frequently, two can mean two separate parts coming out of a whole: "Her heart was broken in two," or "The sheet was ripped in two.
As a synonym for "also," too can mean "in addition," as in "She has six cats, and a dog too." It can mean more than what should be: "That child is too hyperactive!" Too can be used as a way to say "very" or "extremely," as in "She wasn't too stressed out about finishing her paper." In a less formal manner, many children (and adults) may yell, "I am too!" when wanting to contradict someone.
To is the most difficult of the three to define, as it can be used in a variety of ways. It is most commonly used as a preposition, in many different ways. This word can express a direction or a destination, as in "He walked to the shoe store," or "We read from left to right." It can indicate a recipient: "He gave the slimy frog to her." To can express time: "Ten minutes to seven," or something that goes with or is a part of another object: "Where is the top to this jar?"
There are many other uses of the word, as a preposition, adverb, and part of idioms, but it is generally much easier to remember the definitions of two and too, and use to for everything else.