It may seem a small difference, maybe only one or two letters, but it can create a very large disparity in meaning and understanding.

Take the two words, in and into. If you use “in,” you mean “within,” while “into” is speaking of movement “from the outside to inside.”

The distinction is not always made in informal English, but careful speakers and writers show the difference. I put the wrapper into the trash basket, not in. I found my treasure in the basket (it was already in there).

How about the small, yet very broad difference between "effect" and "affect?" The word "effect" is usually a noun indicating the result of some action: "We found the effects of that medication to be detrimental." It can be used as a verb when it means to bring about or create something new: "The speaker tried to effect enthusiasm in his audience"

"Affect" is most commonly a verb indicating to influence or to have an impact on: "You will be able to affect my opinion only with facts." Forms of this word can also be either a verb or an adjective meaning fake or phony: "He was affecting a jolly disposition, but others saw through his affected smile."

Another observation in formal English is the distinction seen "in between" and "among."

"Between" should be used if thinking of two items or comparing items within a group: "Do you know the difference between parallel and perpendicular lines?" "Please explain the distinctions between similes, metaphors and analogies."

Use "among" if you are thinking of a group and not comparing the items: "There were seven reports submitted among them."

Another difference between two words that involves a total of only three letters is with "emigrate" and "immigrate."

"Migrate" means to move; thus, we need only to add im- for into and e- for exit. A person who leaves a country emigrates, while one who enters immigrates. "My grandparents emigrated from Sweden and were among a number who immigrated to the farm country of Nebraska." And don’t forget that these people are then emigrants and immigrants.

Finally, we should look at three small words with very big uses. We’d be hard pressed to function without "who," "that" and "which."

"Which" should refer only to things. "Who" refers to persons only. Either people or things may be represented by the word "that."

This column discusses words/ideas which may be review for many who read it, but that are sometimes forgotten or confused.

— Sandi Ekberg taught high school English in Medford for 30 years, with a special interest in vocabulary, grammar and usage. If you have grammar questions you would like answered, email her at