it

1 :  that one —used as subject or direct object or indirect object of a verb or object of a preposition usually in reference to a lifeless thing took a quick look at the house and noticed it was very old, a plant there is a rosebush near the fence and it is now blooming, a person or animal whose sex is unknown or disregarded don't know who it is, a group of individuals or things, or an abstract entity beauty is everywhere and it is a source of joy — compare he, its, she, they

2 —used as subject of an impersonal verb that expresses a condition or action without reference to an agent it is raining

3a —used as anticipatory subject or object of a verb it is necessary to repeat the whole thing ; often used to shift emphasis to a part of a statement other than the subject it was in this city that the treaty was signedb —used with many verbs as a direct object with little or no meaning footed it back to camp

4 —used to refer to an explicit or implicit state of affairs or circumstances how is it going

5 :  a crucial or climactic point this is it