It was a typical New Orleans jazz band in instrumentation, consisting of trumpet, clarinet, and trombone backed by a rhythm section. The original New Orleans jazz style leaned heavily on collective improvisation, where the three horns together played the lead: the trumpet played the main melody, and the clarinet and trombone played improvised accompaniments to the melody. This tradition was continued in the Hot Five, but because of Armstrong's creative gifts as a trumpet player, solo passages where the trumpet played alone began to appear more frequently. In these brilliant solos, Armstrong laid down the basic vocabulary of jazz improvising, and became its founding and most influential exponent.
The Hot Five was a recording group organized at the suggestion of Richard M. Jones for Okeh Records. All their records were made in Okeh's Chicago, Illinois recording studio. The exact same personnel recorded a session made under the pseudonym "Lil's Hotshots" for Vocalion/Brunswick. While the musicians in the Hot 5 played together in other contexts, as the Hot 5 they were a recording studio band that performed live only for two parties organized by Okeh Records.
There were two different groups called "Louis Armstrong and his Hot Five", the first recording from 1925 through 1927 and the second in 1928; Armstrong was the only musician in both groups.
The original Hot Five was, other than Armstrong's wife Lil Hardin Armstrong on piano, all New Orleans musicians who Armstrong had worked with in that city the 1910s: Kid Ory on trombone, Johnny Dodds on clarinet, and Johnny St. Cyr on guitar and banjo.
On one session in December 1927, Lonnie Johnson was added on guitar.
In 1928 Armstrong revamped the recording band, replacing everyone but himself with his band-members in the Carrol Dickerson Orchestra which Armstrong was playing with Fred Robinson, trombone, Jimmy Strong, clarinet and tenor saxophone, Earl Hines, piano, Mancy Carr (not "Cara" as has often been misprinted) on banjo, and Zutty Singleton on drums.