Writing Skills
From Rsgc Library
Common Word Usage, Spelling and Punctuation Problems
- Its and it's
Its is the possessive form of it (The cat licked its paws) and it's is a shortened form of it is (It's raining again) or occasionally it has (I don't know if it's come). - Oxford Pocket Fowler's Modern English Usage, p. 374
- There, their and they're
TheirItalic text is a pronoun that refers back to a singular pronoun, especially an indefinite pronoun such as anyone, everyone, nobody, or somebody. (Oxford Pocket Fowler's Modern English Usage) (His sister and brother went to their house.) They're''' is a contraction of they are.