Your and Youíre
Their and They're
The same principle applies to their and they're. Their is a possessive pronoun; they're means "they are."
Its and Itís
The word its is the possessive pronoun for the pronoun it. This word shows ownership. It's means "it is." There is no such word as its'.
*** It may be helpful to note here that NO possessive pronoun will ever use an apostrophe.
Who and Whom
Whom is used after a preposition or as the object of a verb:
Who is the subject form of the pronoun and should therefore be used as a subject of a sentence or a subordinate clause.
It is often helpful to reconstruct sentences in order to determine to use who or whom. Also, keep in mind the similarities between "he/who" and "him/whom." If you can substitute "him," you can use "whom." If you have to substitute "he," then use "who."
The antecedent is the noun that the pronoun replaces. Within sentences, the pronoun must agree with the antecedent in number (singular/plural).
The pronoun in this sentence is their, and the antecedent is person. This sentence is not grammatically correct because the word person is singular and the word their is plural.
People most commonly make this mistake in their writing because they are trying to avoid using gender-specific language. However, it is important to make sure that the writing is grammatically correct. Either use "his or her" or change the entire sentence to the plural:
Note: Pronouns like everyone, each, and someone are singular, not plural.
More Information on Pronouns:
A pronoun by definition is a word used in place of a noun. All of the following words are examples of pronouns: she, him, it, your, who, whom, myself, himself, them, whose, which, this, that, these, those, ourselves, each, everybody, everyone, any, anything, several, both, many, neither, some, somebody. You use a pronoun when you want to avoid repeating the noun that precedes it.
When I called Angie, she shrieked with excitement.
The pronoun replaces a specific noun, known as its antecedent. In the previous example, the antecedent was Angie.
Types of Pronouns:
Personal: We use personal pronouns to refer to specific persons or things.
Possessive: This type of pronoun shows ownership.
Relative: Relative pronouns introduce subordinate clauses, which act as adjectives or descriptors in the sentence.
The relative pronoun who refers back to the noun that the subordinate clause who just called me is modifying or describing. Relative pronouns include who, whom, whose, which, and that.
Demonstrative: These pronouns indicate "which?" They include this, that, these, and those.
Indefinite: Indefinite pronouns refer to nonspecific persons or things. They include the following:
Reciprocal: These pronouns indicate a reciprocal relationship between two things: each other, one another