Guinan was the mysterious El-Aurian bartender in Ten Forward, the lounge aboard the USS Enterprise-D. Her race had been scattered by the Borg.

Guinan was born some time before Earth's late 19th century. As a child, she had a Tarkassian razorbeast as an imaginary friend. When troubled she'd talk to it.

(TNG: "Imaginary Friend")

In 1893, she encountered Data from the 24th century, who claimed they were friends from the Enterprise, but Guinan at that time had no knowledge of this.

(TNG: "Time's Arrow", "Time's Arrow, Part II")

Guinan was away from her homeworld when it was assimilated by the Borg.

(TNG: "Q Who")

She traveled extensively over the next several hundred years, eventually becoming a refugee aboard the SS Lakul in 2293.
(Star Trek Generations)
Guinan came aboard the Enterprise-D in 2365 at Captain Picard's personal request. Guinan and Picard shared a long-time relationship.

(TNG: "The Best of Both Worlds, Part II")

Earlier, Guinan had discreetly told Wesley Crusher that she did not know Picard until she came on board the Enterprise.

(TNG: "The Child")

In Ten Forward, she kept a selection of alcoholic beverages for special occasions, in opposition to Starfleet's synthehol regulations, and kept a variety of non-syntheholic drinks, including a bottle of Aldebaran whiskey given to her by Captain Picard.

(TNG: "Relics")

As lounge host, she made herself available to anyone in need, especially to the senior staff, as an informal counselor.

In mid-2366, Lt. Commander Data believed spending time in Ten Forward observing Human social interaction would be beneficial for his android "offspring" he called Lal.

(TNG: "The Offspring")

In early-2369, Guinan, together with Captain Picard, Ro Laren, and Keiko O'Brien, were affected by an anomaly that caused them to revert to the bodies of twelve-year-olds due to the effects of a molecular reversion field. While Captain Picard temporarily stepped down from command, a group of Ferengi commandeered the Enterprise.

(TNG: "Rascals")

Guinan's quarters aboard the Enterprise-D were located on Deck 8, Room 3150. Her office was located on Deck 10, adjacent to Ten Forward.

(TNG: "Q Who")

In late 2368, Guinan was coached by Picard in fencing.
Guinan was born sometime prior to the 19th century, Earth calendar. Her father, at the time, was already over two hundred years old.

(TNG: "Rascals")

In her life Guinan had married 23 times and had "a lot" of children.
(Star Trek Nemesis; TNG: "Evolution")
In 2365, Guinan and William T. Riker attempted to counsel Wesley Crusher regarding his relationship with Salia.

(TNG: "The Dauphin")

Picard once remarked Guinan to be "very selective about whom she calls a friend".

(TNG: "Ensign Ro")

In 2366, Beverly Crusher, while seeing her son socialize with other teenagers, asked Guinan whether she had any children. Guinan replied she had a lot and Beverly inquired whether she had ever had trouble with any one of them.

(TNG: "Evolution")

When Crusher was relieved of duty in 2369, Guinan visited her in her quarters, claiming she sought treatment for her tennis elbow.

(TNG: "Suspicions")

In early 2365, Wesley Crusher was reluctantly preparing to leave the Enterprise and join his mother, who had departed to become head of Starfleet Medical.

(TNG: "The Child")

Guinan would often advise, or rather cheer up, Geordi Le Forge after one of his dates went poorly.

(TNG: "Booby Trap")

In mid-2366, Guinan first approached Worf, introducing him to the Terran beverage of prune juice. Worf called it "a warrior's drink".

(TNG: "Yesterday's Enterprise")