Here are the eleven most common grammar mistakes that truly make some people cringe

Good grammar is the foundation of clear and professional communication. It follows basic sentence structure, punctuation, and spelling rules, ensuring that messages are easily understood.

While English grammar can be complex and sometimes changes, its core principles remain unchanged. Mastering these basics is key to using grammar correctly, says ProWritingAid.

In the workplace, strong grammar skills can make a lasting impression, improve credibility, and even create new career opportunities.

Kyle Wiens, CEO of iFixit, stressed this in a Harvard Business Review article: “If job hopefuls can’t distinguish between ‘to’ and ‘too,’ their applications go into the bin.”

That may seem strict, but many managers have voiced frustration over employees struggling with basic sentence structure, CNBC noted.

To address this, here’s a look at 11 common grammar mistakes based on insights from language experts and hosts of NPR’s You’re Saying It Wrong podcast:

1. I/Me

Use “I” when you’re the one taking action (e.g., “I am running”).

Use “me” when the action is happening to you (e.g., “My friend is running with me”).

2. Lie/Lay

The verb “lie” means to rest or recline on its own (e.g., “I lie down”), while “lay” requires an object, meaning something is being placed down (e.g., “I lay down my head”). A clearer example is “I lay myself down,” where “myself” is the object. It may seem not very clear, but knowing this distinction makes it easier to use correctly.

3. Then/Than

It’s a common mix-up, and autocorrect won’t always help. A quick rule to remember: “Then” refers to the time (e.g., “I’ll go to the meeting, then to lunch”), while “than” is used for comparisons (e.g., “I’m older than he is”).

Fun fact: These words were once interchangeable in Middle English, so they still look alike today.

4. Apostrophes

Many people mistakenly add an apostrophe because a word ends in “s,” but that’s not always correct.

Apostrophes are used for contractions (e.g., turning “here is” into “here’s”) and to show possession (e.g., “the man’s best friend”). However, no apostrophe is needed if the “s” is making a word plural.

5. Its/It’s

Many people mistakenly use “it’s” to show possession, but that’s incorrect. While apostrophes usually indicate ownership, like in “the dog’s bowl,” the word “it” follows a different rule.

Use “it’s” only as a contraction for “it is.” The correct form is “its” without an apostrophe when showing possession. It’s a slight difference, but one that often causes confusion.

6. Lose/Loose

These two words are easy to mix since they look almost the same—the only difference is the extra “o” in loose. However, that small detail can cause big mistakes, like writing “loosing” ground in sales instead of losing it.

A simple way to remember: loose means “not tight,” while lose is a verb that means to suffer a loss or misplace something.

7. There/Their/They’re

These three words sound the same but have different meanings, making them easy to confuse.

“There” refers to a place, like “over there.” “They’re” is short for “they are.” “Their” shows possession, meaning something belongs to a group. Keeping these distinctions in mind can help avoid common writing mistakes.

8. Everyday/Every day

The words “everyday” and “every day” may look similar, but good grammar depends on knowing the difference. “Everyday” (one word) is an adjective describing something routine or common, like an everyday habit. Meanwhile, “every day” (two words) means each day.

A simple trick to get it right: If you can replace it with a specific day, like Monday, then “every day” is the correct choice.

9. Less/Fewer

The words “less” and “fewer” may seem interchangeable. Still, they follow different rules—something many managers quickly point out.

Use “fewer” for things you can count, like “50 fewer trees.” Use “less” for things that aren’t easily counted, such as “less soup in the bowl.” However, when numbers represent a single unit—like time, distance, or percentages—”less” is the right choice, as in “less than 50 miles of the bridge needs repairs.”

10. That/Who

While it may seem small, many managers consider this an annoying mistake. The basic rule is clear: use “that” for objects and “who” for people.

However, exceptions exist. For example, a group like a sales team can be called “that” or “who” since it comprises people. Regarding animals, the rule is to use “that,” even though pet owners might disagree.

11. Your/You’re

This is a mistake spellcheck won’t catch because both words are spelled correctly—even when used the wrong way.

The difference is simple: “You’re” is short for “you are,” while “your” shows ownership. A quick tip to avoid confusion? If you can replace it with “you are,” use “you’re.” Otherwise, “your” is the right choice.

Here is an explanation of why good grammar matters from Andreea S. Calude via TED-Ed: