This Thirteen-million pool is for predicting the date on which the number of articles (as defined by the official article count presented on the Special:Statistics) in the English Wikipedia reaches 13,000,000 (thirteen million). The person who comes closest to the actual date is the winner (of eternal fame). The current number of articles in the English Wikipedia is 6,911,170.
This pool will be closed for entries when the English Wikipedia article count reaches 10,400,000 (80% of 13M), so be sure to place your guess before then.