Geez, all the replies here will be paragraphs long, but i’ll try:
The Dominion is a government from the Gamma quadrent. The leaders of the Dominion are the Founders, or Changlings. Odo is a changling. The Changlings were persicuted by non-Changelings, or Solids, so they formed a government system where they controlled solids. They created the Jem’Hadar to be their soldiers, and the Vorta to be their Administrators. The Vorta were originally a tree-dwelling Ape that helped some Changlings hide, and were evolved forward as a reward. The Jem’Hadar and Vorta worship the Founders as gods.
The Dominion were originally mad at the Federation’s travels through the Bajoran Wormhole and treatened any ship which entered the Gamma quadrent. It was later realized that the Dominion did not control the Gamma Quadrent space near the exit to the wormhole, so their claims were invalid. Changlings entered Alpha quadrent societies disguised as various people, and disrupted activities, most notably by convincing the Cardassian Obsidian Order and the Romulan Tal Shiar to combine forces and destroy the Founders homeworld, but it was a trap and the Obsidian Order and Tal Shiar were decimated. The Destruction of the Obsidian Order allowed a civilian uprising on Cardassia, installing a civilian government. This caused the Klingons to believe that the Founders did this, so they invaded Cardassia. (the Klingons were unduely influenced by a Founder disguised as a Klingon General named Martok) Gul Dukat was full of sorrow to see his beloved Cardassia in ruins, so he joined with the Dominion and installed a government run by him, under the Vorta Weyoun and the Founders. This gave the Dominion a foothold in the Alpha Quadrent.
The Federation and Klingons put aside any general troubles and allied together to face this new threat. A cold war developed, while the Dominion Armed Cardassia for war. Sisko had had enough, and under Starfleet orders, Mined the wormhole entrance. This caused the Cardassian/Dominion fleet to attack DS9, and a war to start. The station was abandoned, left to the care of Bajor, which welcomed the Dominion (because they had no choice). The DS9 battle was a ruse while Klingon/Fed forces attacked dominion shipyards. The tide then turned as the Feds and Klingons were continually pounded by Dominion forces, as the ships are more powerful, and Jem’Hadar troops can be grown in a few days.
A combined Federation/Klingon fleet battled their way to DS9 to stop the de-mining of the wormhole, but arrived seconds too late. Sisko entered the wormhole, contacted the wormhole aliens, and convinced them to take care of a 2500 ship fleet of Dominion ships that were heading for the Alpha Quadrent. The ships promptly disappeared, forcing a Dominion retreat. Dukat went crazy, and a Cardassian named Damar was put in charge of the government. As a drunk, he was thought easy to control.
A stalemate arose between the Fed/Klingons and the Dominion, until Sisko and Garak tricked the Romulans into joining on the Fed/Klingon side. The Alpha fleet was slowly creeping into Dominion space, until the Breen *picture:*http://decipher.com/startrek/cardlists/thetroublewithtribbles/large/thotgor.html joined on the side of the Dominion, and attacked Earth. The Defiant was destroyed by Breen forces and their new energy weapon. here is a cool picture: http://decip
Damar saw the Breen as the new favorites of the Dominion, and the treatment of Cardassians as Second Class citizens, and formed a underground resistance movement. A Giant combined fleet of Fed/Klingon/Rommies attacked the Dominion in a massive attack, and the Cardassian fleet switched sides, and joined the alliance. This forced the Dominion back to Cardassian, and caused the Founder leader to order the deaths of every Cardassian. Damar stormed the Dominian HQ, and took it, but not beofre dying himself. Garak killed the last Weyoun clone, and Odo talked to the Founder leader and convinced her to surrender.
War ends, but then crazy Dukat lets loose some Pah-Wraiths (evil wormhole aliens), and Sisko kills him and the Wormhole aliens take him into the wormhole where he remains to this day (as far as i can tell) Miles becomes a teacher at Starfleet Acadamy, Odo goes home to the Changelings, Worf becomes Ambassador to the Klingons (under new Chancellor Martok), and Rom becomes Grand Nagus of the Ferengi.
Time for lunch…