23 of the Most Common Grammar Mistakes You Need to Stop Making in Your Writing

Even the most educated people sometimes make grammar mistakes. Actually, there is a quite big list of such errors every one of us have made.

We’ve come up with an ultimate list of 23 most frequent errors that you should stop making in your writing.

1. They’re vs. Their vs. There

“Their” and “there” are homophones, i.e., words that have the same pronunciation but different meaning. To always correctly identify which word to use, remember that “there” is the opposite of “here” and refers to a place, while “their” describes possession. Also, “they’re” is just a contraction of “they are” (or “they were”).

We’ve published a comprehensive guide with multiple examples of using their/there on practice.

2. Your vs. You’re

Similar to the previous issue here we have two homophones which are often tricky to use correctly. The word “your” denotes possession while “you’re” is a contraction for “you are.”


This is your decision.

Wow, you’re so fast!

3. Its vs. It’s

Another puzzle that might be very hard to solve even for the most educated people. “Its” denotes possession like “your” or “their,” and “It’s” is a contraction for “it is.” In such cases the ‘s makes people think that there is possession involved as well, which is wrong.

4. Could/would/should of

When you say a contracted form of the phrase “could have” which is “could’ve” it sounds similar to “could of.” This is why sometimes people, especially non-natives, think this is right to write it like this. The thing is the contracted form for could/would/should have is ‘ve, and no “of” involved here.

Bad: We could of been there right now.

Good: We could’ve been there right now.

5. To vs. two vs. too

English is full of homophones, isn’t it? Many language learners mix to/two/too because they sound so similar. To avoid this mistake, you should remember that:

  • “To” is used in the infinitive form of a verb or has the meaning “towards.”
  • “Too” means “also.”
  • “Two” is just a word form of a number 2.

Bad: Let’s go too the party.

Good: Let’s go to the party.

6. Then vs. than

Another top widespread mistake which, again, originates from the similarities of those two words. To avoid errors, remember that you use “than” in comparisons, while “then” can be used to indicate that something follows something else.


She was a better player than him

We will go to school first, then to the playground.

7. Peek vs. Peak vs. Pique

This one is not that popular as “who vs. whom” puzzle, but still can be found quite often. People may even know what word they want to use, but still, make a mistake in writing.

The word “peek” means to take a quick look at something, while “peak” is a top point, say, of a mountain. The hardest word in this sequence is “pique” which means “to provoke.”

There is a piece of mnemonic advice to sort it out in your head fast:

  • You have to reach some threshold to get to the peak.
  • If you peer at something, you are peeking.
  • If you’re piqued by or about something, this means you have some questions about it.

8. Who vs. Whom vs. Whose vs. Who’s

“Who vs. Whom” dilemma is one of the trickiest puzzles the English language has to offer to a learner. We’ve already taken on it in one of our previous posts.

There is a fast way to decide between the two words to see how you can substitute the target word. If you can replace the actor in the sentence with “he” or “she,” then you use “who.” If “him” or “her” looks better than use “whom.”

In turn, “whose” is used to assign ownership, while “who’s” is a contraction for “who is”:

Whose car is that?

Who’s calling the customer today?

9. Who vs. That

One of the trickiest things to figure out. Both words are used for descriptions, and when you describe the person the correct option is “who”:

Bad: Jane is a marketer that has huge experience in working with international customers.

Good: Jane is a marketer who has huge experience in working with international customers.

However, when you’re describing an object, it is correct to use “that”:

Good: This is a car that I’d like to buy one day.

10. Alot vs. A lot vs. Allot

Yep, some people think that “alot” is a real word. It is not, so never use it. If you mean to say about a vast number of something, then you should use “a lot.”

“Allot” is a complicated word you can easily replace, but if you are interested, it means “to assign as a share or portion” or “to distribute by or as if by lot”:

Allot five minutes for each pitch.

11. Into vs. In to

Yes, these could be mistyped as well. To be always correct, you should remember that “into” indicates movement while you can use “in to” in multiple situations when both these words are connected to different other words. For example, if you have a phrase “call in to a game” here “in” is a part of a verb.

So, if you want to write a sentence where someone or something is moving, use “into.”

12. Lose vs. Loose

One more pair of homophones. Really, these two words are spelled so similarly, that there is no surprise, a lot of people make mistakes when writing them.

To avoid such errors, you should know that “lose” is a verb that means that you can’t find something, or you fail to win or solve some task. You can lose a game or your wallet.

In turn, “loose” is an adjective that denotes something “not tightly fastened, attached or held” as outlined by dictionaries.

So, when you are talking about the game, someone could not win, or an object one fails to find, use the word with one “o” – “lose.”

13. Affect vs. Effect

People often confuse these words when talking about changes that were inspired by some event.

Bad: That book effected me strongly.

The truth is that “effect” is the verb used to denote that the change is taking place.

Good: That new play had a significant effect on the audience.

However, if you describe a situation when something happened, and it provoked changes, then “affect” will be OK.

Good: That book affected me so much!

14. Do’s and Don’ts

These words look strange because of apostrophes which are located in different places. The most frequent mistake here is to put an apostrophe in the wrong place for “don’ts”:

Bad: Five Do’s and Dont’s of content creation.

There actually two commonly used styles for these words.  The Chicago Manual of Style offers the following writing: “dos and don’ts.”

15. Me vs. I

Though the absolute majority of language learners correctly identify the difference between “me” and “I” when it comes to using them in sentences, there might be some difficulties

Bad: When you finish the report, send it to John and I.

Good: When you finish the report, send it to John and me.

To identify the correct word to use, search for an object in the sentence. In the example above there are two objects – “John” and “I.” But the word “I” should not serve as an object. There is “me” for that purpose.

16: Run-on Sentences and Comma Splice

Let’s move to the more tricky grammar issues. A run-on sentence arrives when you join two independent clauses without proper punctuation and with no relevant conjunction. This is very similar to the comma splice. The difference is that in such case a comma separate two clauses still with no conjunction.

There are several solutions to the problem you can apply:

  1. Just separate two clauses into independent sentences.
  2. Use a semi-colon instead of a comma.
  3. Use coordinating conjunctions like “and” or “but” to replace the comma.
  4. Subordinating conjunctions like “although,” “if,” “since” suit for this purpose as well
  5. The more elegant and sophisticated solution is replacing the comma with the semi-colon plus transitional word (“however,” “moreover,” etc.)

Bad: John is very good at football, he began playing in the team when he was five.

Good: John is very good at football. He began playing in the team when he was five. (You can use either of five fixes above you like).

17. Pronoun agreement errors

Sometimes people mistype or forget that pronouns should agree in number with the corresponding nouns. The singular noun should have singular referring pronoun.

Bad: Everybody should take their lunch box.

Good: Everybody should take his or her lunch box.

18. Mistakes with apostrophes

In the English language, apostrophes are often used to demonstrate possession. However, there are also possessive pronouns (my, mine, his, her, their, etc.) and after them, you do not use apostrophes.

Bad: I parked next to his’ car.

Good: I parked next to his car.

For “it’s” the apostrophe does not denote possession, it is merely a contraction for “it is.”

Bad: Its a warm day for December.

Good: It’s a warm day for December.

19. Subject/Verb agreement errors

If you write a sentence in the present tense, then there should be an agreement in number between subjects and verbs. If the subject is singular so should be the verb, and if your subject is plural the same applies to the verb linked to it.

Bad: These cars is good for newbies.

Good: These cars are good for newbies.

20. Dangling modifiers

To make your writing crisp and clear you must always put the modifier next to the word it modifies. Everyone should be able to understand this connection at a glance.

Bad: He saw a puppy and a kitten on the way to the office.

Good: On the way to the office, he saw a puppy and a kitten.

21. Using ‘They’ to describe a company

Quite often you can meet the word “they” describing the specific company in blog posts, media articles. People do this because they think about business as a group of people. It seems legit to use “they” in such a scenario, but a word “company” or “business” is not plural. Therefore it is “it,” not “they.”

Bad: Apple is planning to release their new iPhone later this year.

Good: Apple is planning to release its new iPhone later this year.

22. Incomplete Comparisons

This is not a critical issue. However, it makes your writing less confident. Look at this example:

Bad: Our new software is faster, more reliable, and robust.

Here we have a comparison, and an object we try to compare, but we miss another object we are referring to. Shortly speaking, our new software is faster than what? Another software, previous version of our own tool, something else?

The rule is that when you’re comparing something, there should be at least two objects, or the comparison will be incomplete.

23. Possessive Nouns

Usually, possessive nouns have an apostrophe, but it is not always that clear where to put it. It depends on a singular or plural noun it relates to. Here is an example:

All of the boy’s toys were broken.

This sentence is a bit unclear: the apostrophe tells us that there is a specific boy, whose toys are broken, but the word “all” in the beginning indicates that there might be a lot of boys.

Here are some rules to follow:

  • If you have a plural noun then the apostrophe should go after the “s.” (The boys’ toys.)
  • When you have a singular noun that ends in “s,” the apostrophe will go after the “s” again. (Example: the school bus’ yellow color.)
  • If the noun is singular and does not end with “s,” you should put the apostrophe before the “s.” (The boy’s toys).
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