Its (determiner)

1. Belonging to or associated with a thing previously mentioned or assumed.
2. Relating to or belonging to a particular thing.
3. Used to refer to a thing previously mentioned or assumed.
4. Used to indicate possession or ownership of something by something else.
5. Used to indicate the natural or inherent qualities of something.

Origin:

Middle english: from it + -s, translating old english hit, hine.

Examples:

1. The dog wagged its tail.
2. The car has its engine running.
3. The book has its pages torn.
4. The flower has its petals falling off.
5. The tree lost its leaves.