A skimmer was a type of small, near-ground hovercraft-like vehicle used by several races and cultures in the 23rd and 24th centuries. They were used as for personal transportation, auxiliary craft to larger vehicles and facilities, and as military vehicles.
The Ferengi used skimmers for personal transportation for hundreds of years. Skimmer traffic on Ferenginar was along dedicated skimmerways designed and built by the Ferengi Skimmerway Construction Department. Despite the relative simplicity of operating a Ferengi skimmer, accidental vehicular collision was consistently the most common cause of death on Ferenginar. (DS9 reference: Legends of the Ferengi)
A desert flier was a specific type of skimmer used on Vulcan, it featured a more streamlined design than a standard city skimmer and was also somewhat larger (capable of holding several passengers) and could achieve faster speeds. Most Vulcan citizens were not rated to use desert fliers as a standard skimmer was a more logical vehicle for everyday use, desert fliers were instead reserved for those who might require them more emergencies, such as healers. In 2237 a Vulcan healer, at the behest of the young Spock, took his desert flier to a location in L-langon Mountains to treat the younger Vulcan's pet Sehlat, I-Chaya, who had been injured. (TAS novelization: Yesteryear)
Around 2229, Heston Prescott used a skimmer to access a volcano he was attempting to control on planet Elysium. He once came home with his skimmer covered in volcanic dust. (TOS novel: Burning Dreams)
- Prescott is also described in the same book using an aircar, though it is not clear whether the terms aircar and skimmer are interchangeable, or intended to describe the same vehicle.
In 2254 at least four skimmers were attached to the harvester rig Rostok on the agrarian planet Prairie. All were deployed to put out a fire started when the shuttlecraft Icarus crash-landed into the corn fields. Christopher Pike, who had piloted the shuttle, later took a skimmer to try and reach another rig, the Sholakov, and use it's com system. He was shot down by his Klingon attackers before he reached his destination. (EV comic: "The Flat, Gold Forever")
The Bajorans and Cardassians both used skimmers by the mid-24th century. In 2328 the Bajoran Jekko Tybe took Alynna Nechayev and Gwen Jones (Starfleet operatives undercover on Bajor to investiaget claims the Cardassians were planning to occupy the planet) in a skimmer to reach the Korto enclave where they suspected the Cardassians were building up military equipment. The trio hid the skimmer in a barn before proceeding into the enclave through drainage conduits.
When the Cardassians did indeed begin their occupation a short time later armed skimmers led Cardassians troops through the streets, with speakers mounted on them broadcasting a recording of Lale Usbor urging the Bajorans to stay clam and that the Cardassians were their friends and there to help restore peace. (DS9/TLE novel: Day of the Vipers)
In 2353 the Ornathia resistance cell targeted skimmers in an attack on a Cardassian naval base in Musilla province. The cell planned to use four parked skimmers as a target for their ordinance and were hoping the blast would take out as many as sixteen skimmers. (DS9/TLE novel: Night of the Wolves)
In 2373 the Proxcinians purchased seven thousand tritanium-plated assault skimmers from Quark, Gaila and Hagath's arms business on Deep Space 9. Hagath predicted they would be back for more as the Proxcinian War was "just heating up". (DS9 episode: "Business as Usual")
- The TLE novel: Well of Souls describes a vehicles called a landskimmer, which given the name and similar use is probably a specific type of skimmer.