Do not use the pronouns "they" or "their" when referring to a collective noun or an indefinite pronoun. Collective nouns include the terms "all," "everyone," and "everybody." They are collective because they refer to groups of people. Indefinite pronouns such as "each" and "someone," like collective nouns, do not indicate a specific gender . Do not substitute the pronoun "they" for a collective noun or an indefinite pronoun. Instead, try to avoid the need for the pronoun if possible. One way to avoid the pronoun problem is to substitute the word "the" or "a." Use "he or she" or "his or her" as an alternative only if absolutely necessary; this option almost always can be avoided by rewriting the sentence.
Incorrect: Everyone will be required to submit their memorandum at 9:00 a.m.
Better: Everyone will be required to submit his or her memorandum at 9:00 a.m.
Best: Everyone will be required to submit the memorandum at 9:00 a.m.
Incorrect: Each person should provide me with a copy of their schedule.
Better: Each person should provide me with a copy of his or her schedule.
Best: Each person should provide me with a copy of a personal schedule.
Incorrect: A lawyer is the guardian of civil liberties. They protect the rights of those in the citizenry who are unable to protect their own rights.
Awkward: A lawyer is the guardian of civil liberties. He or she protects the rights of those in the citizenry who are unable to protect their own rights.
Best: Lawyers are the guardian of civil liberties. They protect the rights of those in the citizenry who are unable to protect their own rights.
When a first-person pronoun replaces a subject, use "I." When it replaces an object, use "me."
Incorrect: It is me. Correct: It is I.
Explanation: "I" is the subject of the verb "is." Use "I" as a subject and "me" as an object.
Incorrect: The judge threw the gavel at I after the twelfth consecutive objection. Correct: The judge threw the gavel at me after the twelfth consecutive objection.
Explanation: When you are uncertain about using "I" or "me," you may want to ask yourself which word you would choose if writing in the third person. For example, it is easy to conclude that "the judge threw the gavel at her" is correct, while "at she" would be incorrect. Since the pronouns "me," "him," and "her" all are used as objects, you know to use "me" in the first person whenever "him" or "her" would be appropriate in the third person.
It's is a contraction for it is or it has .
Its is a possessive pronoun meaning, more or less, of it or belonging to it .
And there is absolutely, positively, no such word as its' .
A simple test
If you can replace it[']s in your sentence with it is or it has , then your word is it's ; otherwise, your word is its .
Its is the neuter version of his and her . Try plugging her into your sentence where you think its belongs. If the sentence still works grammatically (if not logically) then your word is indeed its .
It's been good to know you. Contraction: it has It's a bird! It's a plane! Contraction: it is
What's the difference between theirs and their's ?
Theirs is the third person plural possessive pronoun - it replaces "their" + noun.
Is this yours or theirs?
He found a book - is it theirs?
I can't find my keys, but theirs are on the table.
Theirs is a better idea.
Theirs is over here.
Though you may see their's written even by native speakers, it is incorrect. Theirs should never have an apostrophe.
The Bottom Line
The idea that theirs needs an apostrophe comes out of the fact that on virtually every other word, 's indicates possession, so English speakers sometimes think theirs should be spelled their's . However, this is always incorrect - theirs is the only correct spelling
Their or theirs
Remember that the third person plural possessive adjective is their : They've sold their house . Don't confuse it with the adverb there , 'in that place' or with they're , which is the shortened form of 'they are'.
The third person plural possessive pronoun is theirs (not their's): If this is theirs, they'd better take it .