"It" as subject

For a discussion of the uses of "it": Pronoun, Dummy, Anticipatory.

Pareekh, Prachi. “It as Subject of Sentence.” GMAT Grammar. 6 Jul. 2006. http://gmat-grammar.blogspot.com/2006/07/it-as-subject-of-sentence.html

“Uses of it.” Internet Grammar of English. The Survey of English Usage. University College of London. Jisc. 1998. http://www.ucl.ac.uk/internet-grammar/minor/dummy.htm