Holosuites are rentable holographic rooms, most famously those operated by Quark on Deep Space Nine, offering private simulations for paying customers.
Holosuites work much like holodecks but are run as a business. Quark's bar on the station's Promenade offered suites upstairs, rented by the hour for a wide variety of programs. Senior officers used them as well, from Julian Bashir's spy adventures to the 1960s Las Vegas lounge where Vic Fontaine sang.
One of Bashir's spy programs became dangerous when a transporter accident stored the crew's patterns in the station computer and the holosuite cast them as characters in the simulation.