The swing style developed in the 1930s and should not be used for earlier records such as 1920s jazz. While the swing style has its roots in the 1920s as jazz developed due to the emergence of musicians such as Lous Armstrong, it took some time for the many different regional jazz styles typical of the 1920s to evolve into the more unified and sophisticated style known as swing. Eventually the "swing craze" of the mid-1930s when big bands like Benny Goodman became hugely popular with younger dancers brought jazz into the mainstream. It is from this period onwards that the swing style can be applied to many jazz records and while opinions about how to define swing obviously vary, it is most typified by the many jazz small groups that recorded from the 1930s onwards (examples are Fats Waller & His Rhythm, Wing Manone's Orchestra, Lionel Hampton's Orchestra, and the many records by the Benny Goodman Trio/Quartet/Sextet). The swing style began in the U.S. but was quickly adopted by musicians worldwide who made recordings in their own countries (UK examples would be Joe Daniels & His Hot Shots or Nat Gonella & His Georgians).
Although many members of the small swing groups worked in big bands, the two styles are distinct. By definition a big band was a large orchestra of at least 12 musicians (and often larger), while a typical swing group of the 1930s was usually a trio, quartet or sextet and most swing recording groups were by at most 7 or 8 musicians. A useful distinction is that a big band featured soloists in the context of tight arrangements using whole sections of the orchestra such as the brass or reeds (seperately or together) while a swing group was more oriented to featuring the musicians as soloists with the backing of a rhythm section only. Of course in some cases big band recordings featured soloists extensively, while small band swing records sometimes featured section work as well as solos - so there is not always a clear distinction. However, the swing tag is most usefully applied to recordings which feature one or more jazz soloists extensively (especially in a small group context).
The swing style was most popular during the 1930s and 1940s, but swing style recordings continued to be made well after that period. Mosty swing is associated with insttumental recordings (although some small band swing records also featuted vocals) however from the 1940s onwards the role of jazz or jazz-influenced singers became more dominant and swing can in some cases also be associated with recordings by pop vocalists such as Ella Fitzgerald and Nat King Cole.
As early as the 1930s swing blended with other genres to create new music styles. In country music, artists such as Bob Wills introduced many elements of swing along with blues to create a genre called Western Swing, which has its own tag. In the blues style there were groups which added elements of swing in their recordings such as the Harlem Hamfats. Gypsy Jazz is a style based on the string jazz of Venuti and Lang's recordings, and again has its own tag. Swing revivals have occurred periodically from the late 1960s to the 2000s. In the late-1980s (into the early 1990s) a trendier, more urban-styled swing-beat emerged called New Jack Swing, spearheaded by Teddy Riley. This has its own network of tags, principally RnB/Swing. In the late 1990s and into the 2000s there was a swing revival, led by Squirrel Nut Zippers, Brian Setzer, Big Bad Voodoo Daddy, and Lavay Smith. Most recently, there is electro swing, which once more has its own tag.