Generally speaking, "it" is a
third person singular pronoun and it is usually used to refer to inanimate things.
Example:
- The book is mine./It is mine.
In the above examples, "It"
still refers to 'book' and 'baby'.
When/How to Use "Its"
Unfortunately, most persons ignorantly
make use of "its" while referring to "it is."
"Its" is a possessive pronoun; thus it is used to show possession.
In this case, it is used to show things own by an inanimate object, and it has
its pronoun reference as "it."
Examples:
1. This house is mine, and its content
are not for sale.
In the sentence above, "its
content" refers to the things belonging to the house, i.e., the things in house.
You can still say, "It is mine and
its content are not for sale." "Its", in this sentence, refers to
things belonging to "it", which is "the house."
2. Government is an interesting subject
because of its content.
Same explanation of example one is applicable
here. The sentence can also take this form: "It is an interesting subject
because of its content." "Its" is showing what government
as a subject contains or possesses that makes it interesting.
When/how to use "It's"
Simply put, "It's" is the
contracted/shortened form of "it is". For example, It is my book/ It's my
book.
In sum, whereas "its" is used
to show ownership, "it's" is the shortened form of "it is."