Apostrophe choices in contractions, possessives and commonly confused forms.
Use “each other” as the reciprocal expression and “each other’s” before a noun to show reciprocal possession. Cambridge also notes that “each other” is written as two words; plain “each others” is not the possessive form.
“Its” is the possessive determiner meaning “belonging to it.” “It’s” is a contraction of “it is” or “it has.” The possessive form does not take an apostrophe, even though many possessive nouns do.
“There,” “their,” and “they’re” sound alike but serve different jobs: “there” commonly refers to place or existence, “their” is possessive, and “they’re” is the contraction of “they are.” A two-stage meaning and expansion test resolves most cases.
“Who’s” is a contraction of “who is” or “who has”; “whose” is the possessive wh-word used to ask or state who something belongs to. Because the forms are homophones in ordinary pronunciation, expansion and possession tests are more reliable than sound.
“Your” is a possessive determiner used before a noun; “you’re” is the contraction of “you are.” The most reliable diagnostic is expansion: if “you are” fits the sentence, use “you’re”; if the word marks something belonging or relating to the person addressed, use “your.”
