Champagne was a sparkling wine, originally made in the Champagne region of France, on Earth. It was traditionally used to celebrate a happy event, and was still used to do so in the 24th century.
In 2293, a bottle of Dom Pérignon was used to christen USS Enterprise (NCC-1701-B). (Star Trek Generations)
In 2364, Lore drugged Data with a tainted glass of champagne under the guise of observing a human custom commemorating the occasion of their meeting. (TNG: "Datalore")
Paul Stubbs wanted to take Deanna Troi to Beth Delta I, to show her the city of New Manhattan "as you've never seen it" while drinking some champagne. (TNG: "Evolution")
Deanna Troi and Devinoni Ral enjoyed champagne when they had a short affair in early 2366. Champagne was also served during a reception aboard the USS Enterprise-D when the nations bidding for the Barzan wormhole took their first look at the phenomenon. (TNG: "The Price")
The script of the episode and the dialog make it clear that Captain Picard had had his fair share of champagne that evening.
Commander William T. Riker, Doctor Nel Apgar and his wife Manua toasted with a glass of champagne when the Enterprise-D was visiting Apgar's research station at Tanuga IV later that year. (TNG: "A Matter of Perspective")
In 2369, Quark got Doctor Julian Bashir a bottle of dry champagne from Korris I to share it with Jadzia Dax during supper. (DS9: "A Man Alone")
In 2370, Worf ordered replicated champagne as part of a dinner he shared in his quarters with Deanna Troi on his birthday, after returning to his proper quantum reality. (TNG: "Parallels")
In 2371, the crew of Deep Space 9 celebrated Julian Bashir's nomination for the Carrington Award with champagne. (DS9: "Prophet Motive")
In an alternate timeline Jake Sisko's wife Korena served champagne for them and Nog at their house in Louisiana. (DS9: "The Visitor")
In 2373, Admiral Charles Whatley replied to Benjamin Sisko's assurance that Bajor would one day join the Federation that he'd keep the champagne on ice. (DS9: "Rapture")
Not long after, Odo replicated two glasses of champagne so he and Doctor Mora Pol could celebrate making a connection with an infant Changeling. (DS9: "The Begotten")
In 2374, the Ramuran tracer Kellin and Commander Chakotay celebrated the success of her mission with champagne. (VOY: "Unforgettable")
In 2375, champagne was served during the celebrations for the installation of the Quantum slipstream drive on board the USS Voyager. Seven of Nine became intoxicated by only one glass of that champagne. (VOY: "Timeless")
After recovering from a Ba'neth attack in 2376, Tuvok was offered a glass of champagne by Neelix, but Tuvok considered tea to be sufficient. (VOY: "Riddles")