While the electric guitar is mostly played with a pick, the bass or jazz bass can be played with either a pick or your fingers. Because of the sensitivity of the pickup on the bass, the two tend to produce somewhat different tones. For example, finger style play can create additional sound from the impact of the strings against the frets, while playing with a pick offers a sharper, more staccato sound. Neither style is better than the other, and there are many famous examples of players using each one. Sometimes, there are conventions of play for a particular genre, but more often it comes down to how a bassist originally learned to play.
In the early 1940s, many jazz musicians, especially African American jazz musicians, started to stray from the popular big band dance music of the 1930s. Their experimentation and quest for deeper expression and freedom on the instrument led to the birth of a new style of music based from Harlem called bebop music. Whereas swing was a popular music designed for dancing, bebop was a "musician's music" designed for listening. During the bebop era, given that bands no longer had to accompany dancers, bandleaders could speed up the tempo. Bebop was also much more based on improvisation, in comparison to the heavily arranged big band scores. Bebop musicians would take an old standard and re-write the melody, add more complex chord changes, resulting in a new composition.
Bassists often play a bass line composed by an arranger, songwriter or composer of a song—or, in the case of a cover song, the bass line from the original. In other bands—e.g., jazz-rock bands that play from lead sheets and country bands using the Nashville number system—bassists are expected to improvise or prepare their own part to fit the song's chord progression and rhythmic style.
In some cases, to play the bass through PA amplification, it is plugged into a direct box or DI, which routes the signal to the bass amp while also sending the signal directly into a mixing console, and thence to the main and monitor speakers. When a recording of bass is being made, engineers may use a microphone set up in front of the amplifier's speaker cabinet for the amplified signal, a direct box signal that feeds the recording console, or a mix of both.