Here's a list of common grammar mistakes that many people make in English. Often people interchange these words with each other, not understanding the definition of each word and the differences. Here's a quick and simple guide to help out:
1. Their, There and They're
Their = Belonging to or associated with the person.
There = in, at, or to that place or destination.
They're = they are.
2. Your and You're
Your = Belonging to or associated with the person.
You're = You are.
3. Its and It's
Its = Belonging to or associated with a thing.
It's = It is
4. Affect and Effect.
Affect = Have an effect on, make a difference.
Effect = A change which is a result or consequence of an action or other cause.
5. To, Too and Two.
To = Expressing motion in the direction of.
Too = In addition, also. To a higher degree than is desirable.
Two = 2.
6. i.e and e.g
i.e and e.g are both latin abbreviations. E.g means "For example" and i.e means "In other words."
7. Who, Whom, Whose and Who's
Who = What or which person or people.
Whom = Used instead of "who" as the object of a verb or preposition.
Whose = Belonging to or associated with which person.
Who's = Who is.
8. Then and Than
Then = At that time; at that time in question.
Than = Introducing the second component in a comparison.
9. Assure, Ensure and Insure
Assure = Tell someone something positively to dispel any doubts.
Ensure = Make certain that (something) will occur or be the case.
Insure = Secure or protect someone against (a possible contingency).
10. Farther and Further
"Farther" refers to a physical distance, whereas "further" refers to a figurative distance.
11. Here, Hear and Hair
Here = In, at, or to a place or position.
Hear = Listening to somebody.
Hair = The strands that grow out of your head.
12. Colons, Semicolons and Dash
The common use of the colon (:) is to introduce a list of items.
The common use of the semicolon (;) is to join together two clauses that could be separate sentences, creating a longer sentence.
The dash (-) can be used in place of the colon, to emphasise the conclusion of your sentence. Although, the dash is less formal than the colon.