The contrabass may also be referred to as the double bass, and in popular idioms such as jazz as "stand up bass." The contrabass is a transposing instrument, which means that when the note written on the page is played, it sounds a different pitch. In this case, the contrabass sounds one octave lower than written. The contrabass is a large instrument typically taller than 6 feet, and bassists either sit on a tall stool or stand while playing.

Unlike the other string instruments, the contrabass' open strings are a perfect 4th instead of a perfect 5th. This is due to the size of the instrument. To demonstrate the size, in lower positions the distance of a major 2nd is over four inches. Double stops are also somewhat limited by the size of the instrument, and these work best when one of the strings is an open string. Tuning the instrument in fourths helps alleviate the issues caused by its size, but it is important to keep the size of this instrument in mind when writing for it. The contrabass has a very wide pitch and dynamic range. Like the cello, the contrabass can read the bass, tenor, and treble clefs; however, in ensemble playing, the tenor clef is rarely used. Instead, ledger lines in the bass clef, or using the treble clef for extremely high passages, is preferred. Also like the cello, it is best to switch to appropriate clefs for longer passages instead of just for one or two notes.

In some scores, the contrabass is written below the E string. This has become more and more common over the past 50 years, and now composers can expect that professional players will be able produce these notes by equipping their bass with a "C-extension." This device replaces the E string with a longer string. Near the scroll are four triggers that stop the string at the pitches E, E♭, D, and D♭. Amateur and younger players without a C-extension will simply play the pitches up an octave.

Natural harmonics harmonics work really well on the contrabass because, as previously stated, they become easier to produce on larger instruments. Artificial harmonics, on the other hand, are often avoided. Generally, artificial harmonics should be avoided. The performance of artificial harmonics where the node is a perfect 5th, perfect 4th, or major 3rd above the stopped note are practically impossible. Advanced players can often produce the artificial harmonic where the node is a minor 3rd above the stopped note, but this should be reserved for special cases and for professional players. But again, natural harmonics are extremely effective on the contrabass and can be either bowed or plucked.

Due to the large size and resonance of the contrabass, pizzicato, sul tasto, and sul ponticello are also very effective. These techniques have a wide dynamic range and provide additional colors for the contrabass.

The low E string on the contrabass is often described as "dark" and "subdued." The pitch is so low that the first harmonic of the open string can sound more present than the fundamental note. The strings become more harmonically rich from the A string to the G string. The D and G strings are typically thought of as the most expressive strings.

In more traditional music, the contrabass is relegated to playing the bass line of the harmony almost exclusively. As previously mentioned, pizzicato is very effective and can be quite resonant providing composers means for rhythmic gestures. These practices are still prominent today, but beginning in the 20th century, composers began to explore the diversity of the instrument and it has become a candidate more and more for melodic and expressive music.