Are You Making These Common Grammar Mistakes?

As the resident grammar police at Foresite, I’ve made a list of grammar mistakes that people make quite often. Are you making some of them, too?


Starting off with an obvious one here, but so important. Your is a possessive pronoun used to say things like “Your coat is over there.” You’re is a contraction of the words “you” and “are,” and can be used to say something like “You’re the best.”


Another obvious one. Here’s how I remember it: too is “too much” because it has an extra O. Two is a number.


According to Purdue OWL (my grammar best friend), apostrophes are used to¬†form possessives of nouns, show the omission of letters (like contractions) and¬†indicate certain plurals of lowercase letters. One big issue I see all the time is adding just an apostrophe when someone’s name ends in -s. This is incorrect.

Wrong: James’

Right: James’s

The dreaded semicolon

Semicolons are used to separate two independent clauses, which means the two phrases can stand as sentences alone. So, instead of saying, “My professor is intelligent. I have learned a lot from her.” you can say, “My professor is intelligent; I’ve learned a lot from her.”


“Who’s” is a contraction for the words “who” and “is,” while “whose” is a possessive pronoun used to say something like “Whose coat is this?”