Quark is the Ferengi bartender/civilian administrator. He runs several entertainment concessions along the promenade, including the main bar, restaurant, gambling house, and the holo-suites upstairs where your every fantasy can be played out.

He spends most of his time behind the bar. If there is some scam being run in the sector it often involves him. But beyond the malevolence he is a charming host, in a Ferengi sort of way, and forges an interesting relationship with Sisko. They actually enjoy sparring together now and then. The Ferengi lends a hand to dissolve a problem for the commander -- as long as there's something in it for him.

His completely sexist attitude makes Kira an obvious adversary, and he is consumed with passion for Dax. He is willing to help the station's crew - as long as there's something in it for him.

The Ferengi are ugly, sexist, greedy little aliens who are interested only in profit and getting their hands on anything of yours they happen to fancy.

He has been on the station for at least four years prior to the Federation takeover in "Emissary."

Quark's Ferengi business license was revoked by FCA on stardate ~49930 (in year 2372, "Body Parts"), but was later reinstated with his mother's help on stardate ~50740 (in year 2373, "Ferengi Love Songs").

Quark crash-landed his ship on Earth in 1947 with Rom, Nog, and Odo ("Little Green Men"). This is known to be the Roswell incident.