"A fantasy encounter with danger, romance, thrills... created for your personal entertainment by the brothers Quark."
A holosuite used transporter technology to create holographic images in much the same way that a holodeck did. However, holosuites were in wider use than holodecks and were not limited to starships. There was also more variation in holosuite design than holodecks.
The Ferengi entrepreneur Plegg was credited with designing the first modular holosuite and was responsible for its subsequent spread across the galaxy. (DS9: "The Alternate") Ferengi operators particularly advertised their holosuites' potential for acting out sexual fantasies. (DS9: "Meridian", "The Emperor's New Cloak")
Generally, holosuites were much smaller than holodecks. They were intended for individual or very small group usage unlike holodecks which were known to accommodate dozens of people. (TNG: "Homeward") Aboard Sovereign-class starships, holosuites could also be used by several people. Although, the term holosuite may have just have become more widespread and used interchangeably with the word holodeck. (Star Trek: First Contact)
Quark offered the bidders at his auction free use of the holosuites to calm them down after Q told them about the doom of Deep Space 9. (DS9: "Q-Less") He also offered the Wadi use of the holosuites after he was caught cheating at the dabo game. (DS9: "Move Along Home")
The same year Julian Bashir proposed that the visiting Federation ambassadors Taxco, Vadosia, Lojal, and Lwaxana Troi used the holosuites at Quark's Bar. Taxco was insulted by the proposal to use these "disgusting Ferengi sex programs". (DS9: "The Forsaken")
Background information Edit
Herman Zimmerman commented that the holosuites "are like the holodeck of Next Generation and we can program pretty much any kind of experience for any kind of location we want to. But what we are doing on Deep Space Nine that we weren't able to do on Next Generation is we see the inside of the holodeck and we see the machinery that runs it. When we did Next Generation we were in a budget constraint that made us do a set that is a wireframe look; it's a grid of squares when the holodeck is not activated and they just see a black void with yellow grids. In the Cardassian holodeck when the lights go off, so to speak, you see the machinery that creates the imagery. It's a step forward for us and it's something we've always wanted to do on Next Generation and we were never able to achieve". (The Deep Space Log Book: A Second Season Companion)
In the Deep Space Nine book trilogy Millennium it is revealed that Jadzia Dax and Worf enjoyed using Quark's holosuites to re-enact the events from TOS: "Day of the Dove". Dax would dress as an Enterprise crewmember, while Worf would take on the role of Kang.