What Are The Most Common Grammar Mistakes?

Grammar is a polarizing topic. Some people (maybe you?) love it and are nerds about it. Other people (also maybe you?) hate it because it’s a fickle friend. You know what I’m talking about if you’ve ever written with Grammarly active.

But love it or hate it, good grammar matters. As Jeffrey Gitomar, an American author and speaker on sales, once said, “Your grammar is a reflection of your image. Good or bad, you have made an impression. And like all impressions, you are in total control.”

If a renowned salesperson believes in the power of grammar, then we probably should, too.

Fortunately, like most things, grammar is knowledge, and knowledge can be learned. So, even if you’re not great with grammar yet, you can become so with some practice.

To help you practice, we’ve compiled a list of the most common grammar mistakes people make while writing. Once you are aware of, have memorized, and fixed these common mistakes in your writing, it will be significantly improved and require less revision after drafting and before publishing.

Without further ado, here are the mistakes.

Mistake 1: Subject-Verb Agreement

The subject and verb in a sentence should always agree in number, person, and gender.

Now, what the heck does that mean?

It means that the verb (singular or plural) should agree with the subject (singular or plural).

For example, “the dog ran” and “the dogs ran” are both correct, but the present tense is “the dog runs” and “the dogs run.” Or, “a dog runs” but “two dogs run.” You wouldn’t say, “Two dogs runs.”

“But what about gender?” you might ask. Fortunately for us English speakers, English doesn’t use gender in verbs, unlike other languages like French or Spanish. When speaking, writing, or editing in those languages, check for subject-gender agreement, too.

Mistake 2: Comma Splices

Comma splices are one of the most common grammar mistakes.

What is a comma splice? A comma splice is when a comma is used to link two independent clauses or sentences instead of using a semicolon, colon, or other conjunction like an em-dash.

Here is an example of a comma splice:

Sally went to the doctor, she said everything is fine.

Here is the corrected grammar:

Sally went to the doctor; she said everything is fine.

Another way to correct the first sentence would be to rewrite it to this:

Sally went to the doctor, who said everything is fine.

Mistake 3: Run-On Sentences

A run-on sentence is the sentence that never ends (did I get “this is the song that never ends” stuck in your head?)

The proper definition of a run-on sentence is a sentence that joins two or more independent clauses without proper punctuation or conjunctions. Social media is rife with run-on sentences (and many other things, of course), so you’ll probably recognize a run-on pretty easily.

For example:

Sally went to the doctor and she said everything is fine but then we called and she said that there were some issues with the scan machine and I needed to come back next week to do another one and she wants to know when I can come in.

To correct that run-on, try this on for size:

Sally went to the doctor, who said everything is fine. I called, and she said that there were some issues with the scan machine, which means I need to come back next week for another. She wants to know when I can come in.

Run-on sentences are usually best fixed by breaking them into multiple sentences.

Mistake 4: Missing or Unnecessary Apostrophes

Get ready to cringe, grammar nerds. Missing and unnecessary apostrophes are all over Internet writing, but they’re one of the most common grammar mistakes and deserve to be fixed.

The most common apostrophe mistakes are:

  • Adding an apostrophe to a plural word – for example, “Just Say No To Drug’s.”
  • Using an apostrophe with possessive pronouns – apostrophes are not needed with terms like his, hers, theirs, yours, ours.
  • Adding an apostrophe to proper nouns that end in “s” – this one varies by style guide, but by and large, an apostrophe is not needed at the end of a proper noun, like a last name, that ends in “s.” That said, both “Dickens’ books” and “Dickens’s books” can be correct at different times. Make sure to keep usage consistent in the same piece!
  • Forgetting that contractions are shortened versions of words – the most common mistake is writing “its” when trying to write “it is” or “it’s.”
  • Adding an apostrophe to abbreviations – an apostrophe is not needed after an abbreviation like DVD (it’s DVDs, not DVD’s).

Mistake 5: Missing or using unnecessary hyphens.  

Here are ways that hyphens are commonly misused:

  • Using a hyphen when it’s not needed. Some examples are using them with adverbs that end in “-ly” or include “very.” For example, “the dimly-lit room” and “very-dimly lit” are both incorrect.
  • Using a hyphen when designating ages. For example, “the girl is seven-years-old” is incorrect. The correct is “the girl is seven years old.”
  • Using a hyphen when there is more than one proper noun within a compound adjective. Names like The Red Hot Chili Peppers are never hyphenated.
  • Including hyphens when an otherwise-hyphenated phrase is in quotes. For example, you could write she became increasingly tired of his “holier than thou” attitude.
  • Using a hyphen when replacing a comma or semicolon. For example “She went to the store – she needed some pickles” is incorrect. The correct usage is “She went to the store; she needed some pickles.” Of course, a more straightforward sentence is “She went to the store for some pickles.”
  • Being inconsistent with hyphen usage. For example, using “homemade jam” in one chapter and “home-made pickle” in another is inconsistent.
  • Misspelling numbers: For example, “twenty eight people attended the house party” is incorrect. “Twenty-eight people attended the house party” is correct.

Mistake 6: Sentence fragments

A sentence fragment is a partial sentence that lacks either a noun or a verb. For example:

Ran to the store.

This is ok when sending an SMS/text to your partner to tell them where you went, but it’s incorrect in writing when outside a quote.

“She ran to the store” is correct. “He wrote,’Ran to the store, be back soon.'” is also correct because that’s what he wrote.

Mistake 7: Lack of pronoun or antecedent agreement

Pronouns should agree in number, gender, and person with their antecedent (the word that comes before).

For example, “Sarah and I went to the movies. We saw ‘Jurassic Park.'”

You could use a singular pronoun, though, in this case: “Sarah and I went to the movies. She had a drink, and I ordered popcorn.”

When multiple pronouns are preceded by “every” or “each,” a singular pronoun is used. For example, in the following sentence “its” is used because family and business are preceded by “every,”:

Every family and business must do its part to conserve energy.

Mistake 8: Poorly integrated quotation marks. 

Poorly integrated quote marks can be either of the following:

  • A complete sentence that is a quote.
  • A quote that is not introduced in the sentence.

For example, simply writing “That’s not quite right.” on its own line outside of the context of a full conversation.

A quote not introduced in a sentence looks like this:

James and Sally are big Rockies fans. “They’re the best.” They go to as many games as possible.

To correct this, write the sentence this way:

James and Sally are big Rockies fans. “They’re the best,” Sally told us. The couple goes to as many games as possible.

Mistake 9: Using these commonly confused words: 

Commonly confused words include:

  • “their”, “there”, and “they’re”, (Their kids are there but they’re not listening very well.)
  • “your”, and “you’re”, (You’re correct that your kids are wild.)
  • “its”, and “it’s”, (It’s correct to say that your dog and its puppies are adorable.)
  • “affect”, and “effect”, (The weather affects my mood to great effect.)
  • “me”, and “I”, (I don’t know. Me either.)
  • “to”, and “too”, (I love to eat cake, too.)
  • “alot”, “a lot”, and “allot”, (A lot of people are allotted tickets to the Sum41 show. “Alot” is not a word.)
  • “into”, and “in to”, (I walked into the apartment and put the drink in to the fridge.)
  • “lose”, and “loose”, (Don’t lose those loose cows!)
  • “then”, and “than”, (I use less than Sally, then I go home.)
  • “of”, and “have”.   (Should have, not should of.)

Mistake 10: Fewer vs. less

This one’s changed a bit as language morphs, with many people using “less” for both words, but technically, “fewer” and “less” are different words to be used at different times.

“Fewer” is used when there are definite numbers, while “less” is used when the amount is abstract or can’t be counted.

For example:

I have three fewer fish than James.

That car is worth less than mine because mine’s fancy.

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