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Brush up your grammar.

If grammatical mistakes send you into a fit, fury, or frenzy, we feel your pain. At the very least, misused and ill-chosen words make us want to uncap our red pens and start making corrections. With that in mind, we’ve put together a list of our biggest grammatical pet peeves, cringe-worthy mistakes we’d like to set right. Some grammatical mistakes are perennial stumbling blocks, so take notes and eradicate these linguistic mishaps from your written correspondence and spoken conversations once and for all.

Affect vs Effect 

‘Affect’ is a verb indicating that something is influencing or changing something else. Merriam-Webster defines this usage of ‘affect’ as “produc[ing] an effect upon; to produce a material influence upon or alteration in.”
Example: “We were affected by the news.”

‘Effect’ is usually used a noun. Merriam-Webster defines the noun form of ‘effect’ as “something that inevitably follows an antecedent (such as a cause or agent),” while the lesser-used verb form of ‘effect’ indicates the action “to cause to come into being.”
Examples: The new idea will have the same effect as the old one. The germ effected the illness.

Fewer vs Less

‘Fewer’ should be used when referring to countable things (e.g., people, cities, ingredients, ideas).
Example: There are fewer reasons to comply.

'Less’ is the appropriate modifier for singular nouns and things with uncountable mass (e.g., money, happiness, energy).
Example: They have less time now.

Its vs It’s

‘Its’ is a possessive term and can be used before a noun to indicate that one thing possesses another thing.
Examples: The dog wagged its tail. They chose the idea on its merits alone.

In contrast, ‘it’s’ is a contraction meaning “it is.”
Examples: It’s my birthday. It’s going to rain this afternoon. I think it’s a good idea.

There vs Their vs They’re

‘There’ indicates place.
Examples: There is a house at the end of the street. Put the crayons over there.

‘Their’ is a possessive pronoun. It is used to indicate that something belongs to or is associated with a person or a group that has already been mentioned.
Examples: Their cat is taking a nap. You'll find their piano in the living room.

‘They’re’ is a contraction of the two words ‘they’ and ‘are.’
Examples: They’re going to the carnival. I think they’re on their way.

Which vs That

‘Which’ should be used when introducing a nonrestrictive clause, one that can be removed without altering the meaning of the sentence and is not essential to understanding the sentence.
Example: The end of the story, which was sad, is memorable.

On the other hand, ‘that’ should be used when introducing a restrictive clause (a clause that, if removed, would alter the meaning of the sentence or make it difficult to understand).
Example: The solution that was chosen has many critics.

Who vs Whom

‘Who’ refers to the subject of a sentence. In the sentence, it can usually be replaced by ‘he’ or ‘she’ and still be grammatically correct.
Examples: Who wants to go the zoo? Who should plan the trip? 

‘Whom’ refers to the object of a preposition or a verb. It can usually be replaced by ‘him’ or ‘her’ in the sentence and still make sense, though the sentence may need to be rearranged for it to remain intelligible.
Examples: To whom did you speak? Whom should I ask?

Your vs You’re

‘Your’ is a possessive adjective and should be used when indicating possession.
Examples: Your dog does tricks. Did you walk your dog?

‘You’re’ is a contraction of the words ‘you' and 'are’ and should be deployed in the same manner as the phrase "you are."
Examples: You’re going on an adventure. I think you're going to be late.

For more lessons from the world of grammar, peruse If You Can Spot All 13 Grammar Mistakes in This Letter You’re Probably an English Teacher, What’s the Difference Between Y’all and Ya’ll?, and How to Make Your Last Name Plural.

WATCH: What's the Difference Between Y'all and Ya'll?

What are your grammatical pet peeves? Let us know what mistakes always make you cringe.