1. Since/Because

People will use these two words interchangeably, which is technically incorrect because they don't mean the same thing. "Since" refers to time, so you would say, "Since I graduated from college, I've received several job offers." When you use "because," it should refer to the cause of something: "I'm full, because I ate an entire cheesecake." Don't be embarrassed if you've made this error before, because it's one of the most common grammar mistakes.

2. Who/Whom

"Who" is equivalent to "he" or "she," while "whom" is equivalent to "him" or "her." If you're trying to ask someone whom they are going to vote for to be president, you'd use "whom," because they would respond with, "I'm voting for him," not "I'm voting for he." It's difficult to understand at first, but once you get used to it, it'll be easy.

3. Fewer/Less

When you shop at a store and see a sign that says, "10 Items or Less," they're using incorrect grammar. You should use "fewer" when referring to objects that you can actually count, like flowers in a bouquet. Use "lesser" when referring to ideas that you can't actually count, like successfulness or happiness.

4. There/Their/They're

"They're" is a contraction that means "they are." "Their" shows possession, so you would say, "My parents love their dog." "There" shows location, so you would say, "Please place the book down over there." You can even use all three words in the same sentence: "They're going to their favorite store that is over there, by the lake." Once you get the hang of it, it'll become second nature to you.

5. Nauseous/Nauseated

When you feel sick, you shouldn't say that you're feeling nauseous. You should say that you feel nauseated. "Nauseous" means that something is capable of producing nausea in others. So you would say, "Those leftovers are nauseous" and "After I ate the leftovers, I felt nauseated."

6. Farther/Further

Use "farther" when you can measure a distance. You can say that your house is farther away from school than your friend's house is, and it would be grammatically correct. Use "further" when you're discussing immeasurable things. You can say, "I will not discuss this any further."

7. Then/than

"Then" represents time that has passed, while "than" is a comparison word. You can say, "I went to the store, then I went to the movie theater," and you can also say, "I'd rather go to the store than to the movie theater." The words mean two completely different things. Don't assume that they're similar just because they look similar.

Everybody makes mistakes, so don't feel bad if you're guilty of making every error on the list. As long as you learn how to fix your mistakes, you should feel like a smartie. What grammatical error do you find the most frustrating?