it's not vs it it isn't

ActuaryalfredI always saw these two. Which one should we use?

Both are acceptable.

"It's not" is a shortened version of "(It is) not". The apostrophe stands in for the missing letter "i"

"It isn't" is a shortened version of " It (is not)". The apostrophe stands in for the missing letter "o".

Either is correct.

The one you shouldn't use is -- 'it it isn't'.

DavkettThe one you shouldn't use is -- 'it it isn't'.

Yup.

Either is fine.

Both are contractions of "it is not"; so either is grammatically correct. The one omits the 'i' in 'is', and the other omits the 'o' in 'not'.

There is a slight difference in emphasis, though. For example, to emphasise the negative, such as when you are contradicting someone, you should use "it's not". To emphasis the subject, you use the other form.

This is way over-due since you posted this on may..but

*yours

That looks like a useful distinction, alhough I still think that either would be fine here.

But not "your's". No apostrophe. It's "yours"...... always

Both are acceptable, but use "it's not" when you want to emphasize the "NOT" message. For example, it is unacceptable to drink at work, you may want to state "it's not acceptable to drink alcohol at work".

This is a very good answer. Thanks a lot!