The seven seals are the way the first process for the annihilation of humanity have begun. The first four seals opened as each Horseman makes his/her decision to side with darkness.
The exact date was June 4, 2008.
The seventh seal broken will cause the Rapture. Never coming.
The seven seals is a phrase in the Book of Revelation that refers to seven symbolic seals that secure the scroll. When the first seal is opened the Four Horsemen of the Apocalypse are summoned, each with their own specific mission. The opening of the fifth seal releases the cries of martyrs. The sixth seal prompts earthquake cataclysmic events. The seventh seal cues seven angelic trumpeters who in turn cue the seven bowl judgements and more cataclysmic events. 
The order the seals were broken in the series (Death - War - Pestilence - Famine) is very different to the order that was featured in the Book of Revelation (Pestilence - War - Famine - Death).