A strathspey is a type of dance tune in 4/4 time. It is similar to a hornpipe but slower and more stately, and contains many dot-cut 'snaps'. A so-called Scotch snap is a short note before a dotted note, which in traditional playing is generally exaggerated rhythmically for musical expression. An example of a strathspey would be the song "The Bonnie Banks O' Loch Lomond", provided it is sung staccato: Other examples are the tunes to Auld Lang Syne (based on Sir Alexander Don's Strathspey) and Coming through the rye (based on an old strathspey tune called The Miller's daughter).

Because the strathspey rhythm has four strong beats beats to the bar, is played quickly (generally ranging from 108 beats per minute, for Highland Dance, up to 160 beats per minute, for stepdance), and contains many dot-cut 'snaps,' it is a rhythmically tense idiom. Traditionally, a strathspey will be followed by a reel, which is in 2/2 with a swung rhythm, as a release of the rhymthic tension created during the strathspey.

It has been hypothesized that strathspeys mimic the rhythms of the Scottish Gaelic language. Among traditional musicians, strathspeys are often transmitted as canntaireachd, a style of singing in which various syllables stand in for traditional bagpipe ornaments.

The dance is named after the Strathspey region of Scotland, in Moray and Badenoch and Strathspey. Strathspey refers both to the type of tune, and to the type of dance usually done to it (although strathspeys are also frequently danced to slow airs). The strathspey is one of the dance types in Scottish country dancing. A Scottish country dance will typically consist of equal numbers of strathspeys, jigs and reels. The strathspey step is a slower and more stately version of the skip-change step used for jigs and reels. The strathspey also forms part of the musical format for competing pipe bands - modern high grade bands are required to play a March, Strathspey and Reel for competition purposes.

The strathspey may have originated in bagpipe tunes; many newer strathspeys were written in the 18th and 19th centuries by composers such as William Marshall and James Scott Skinner, who utilised the full range of the fiddle to produce many memorable tunes. Skinner distinguished between dance tunes, which retained the staccato bowing (Laird o Drumblair), and airs which were to be listened to (Music of Spey). More recently, Muriel Johnstone has written some elegant piano strathspeys. These days there are at least four, some would say seven, varieties: the bouncy schottische, the strong strathspey, the song or air strathspey, all three of which can be enjoyed for dancing, and the competition strathspey for the Great Highland Bagpipe, primarily intended as a display of virtuosity. Although band and solo competition piping generally involves a complicated, heavily ornamented setting, traditional pipers often play simpler, more rhythmically driven versions.