it

it [-s, -'s] pron

OE hit; third person singular neuter pronoun.

1. [Anaphoric reference, pointing back to a previously-mentioned noun in the text] that thing; the one mentioned.
2. [Cataphoric reference, pointing forward to a subsequent noun in the text] the event; this thing.
3. [Exophoric reference, pointing to a noun not mentioned directly in the text; “It sifts” = “Snow sifts”] this; the thing being described.
4. [Phatic “dummy” subject; “It will be Summer” = “Summer will happen”] someday; at some time.