Using pronouns makes English sound and read a lot better. Rather than writing, for example, Judy loved Jim. Every time Judy saw Jim, Judy felt a warm glow, we can write Judy loved Jim. Every time she saw him, she felt a warm glow. Much nicer with pronouns!
Now, possessives show ownership of some sort or other. It doesn't have to be the physical ownership of "things", but can also refer to emotions and other attributes.
We're used to adding "apostrophe s" to form possessives of regular nouns — Fred's tea, the donkey's bad temper, the book's cover. But possessive ponouns are different. Very different. Here's the rule to remember:
Possessive pronouns do not use "apostrophe s" AT ALL.
The main possessive pronouns are: my, mine, yours, his, her, hers, its, our, ours, their, theirs, your, and yours.
Note well the use of ITS. I discuss ITS and IT'S elsewhere on this site. Remembering that possessive pronouns do not use "apostrophe s" should help you to remember the correct spelling for this tricky word.
(There is, of course, always some exception to the rule, otherwise it wouldn't be English, would it? In this case, one's is different, as in One's health is so important, you know.)
Practise your possessives to get some practice in your newfound knowledge of possessives!
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