In jazz improvisation, enclosures are a melodic technique used to approach a target note by surrounding it with adjacent notes. Instead of landing directly on the note, a player "encloses" it by playing the neighboring tones first, usually one or two half steps above and/or below, creating tension and release when finally resolving to the intended pitch.

For example, if the target note is a C, a musician might play the notes D (a whole step above), B (a half step below), and then resolve to C. This approach adds a smooth, jazzy flavor to solos by introducing chromatic movement and emphasizing the strong tonal center.

Enclosures are especially common in bebop and post-bop styles, where improvisers use them to navigate chord tones within complex harmonies. They help make lines sound more fluid and connected rather than jumping abruptly from one note to another. By mastering enclosures, jazz soloists can add nuance and sophistication to their improvisations, making their solos more interesting and expressive.

In summary, enclosures in jazz improvisation are a deliberate way to "frame" a note by playing surrounding tones first. This technique enriches melodic lines with chromaticism and smooth transitions, contributing to the characteristic sound of jazz solos.