The choice between "it's" and "its" depends on the context:
-
"It's" is a contraction for "it is" or "it has." For example:
- "It's going to rain today." (It is)
- "It's been a long day." (It has)
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"Its" is a possessive pronoun, meaning "belonging to it." For example:
- "The dog wagged its tail."
A good way to remember the difference is that if you can replace the word with "it is" or "it has," then you should use "it's." If you are indicating possession, use "its."