The bass guitar is one of the several variations of the classical guitar tuned to a different pitch; in this case a very low one. It is a stringed instrument played mainly with the fingers or thumb or with the use of a plectrum.

The construction of the bass guitar is such that it is similar to the electric guitar, only with a larger body. Also, it has a longer scale length and neck with four, five or six strings tuned to the same pitches as those of the double bass. The body of the bass guitar is most often made of wood, though other materials can also be used, such as graphite. The most common type of wood used is alder for the body, maple for the neck and rosewood for the fretboard. This hefty instrument often has more strings and two necks. One neck has normal frets on the key, to which six strings have been applied, while the other neck, that has no fret, can have as many as twelve chromatically tuned bass strings. However, the standard design for the electric bass guitar has four strings, tuned E, A, D and G, in fourths such that the open highest string, G, is an eleventh (an octave and a fourth) below middle C, making the tuning of all four strings the same as that of the double bass. Almost all electric bass guitars use magnetic pickups. Sometimes, though non-magnetic pick-ups may also be used.

The bass guitar can be played in a number of different ways. The strings of the guitar may be plucked, slapped, popped, tapped or thumped. While being plucked with the fingers, the index and middle fingers are used. It may be plucked at any point between the bridge and the point where the hand on the fret is holding down the string. Depending on the point where the string is plucked, different timbres may be produced. The instrument is mainly used for the purposes of transposing as it is notated in bass clef an octave higher than it sounds (as is the double bass) in order to avoid the excessive use of ledger lines. Just like the electric guitar, the bass guitar is also plugged into an amplifier and speaker for live performances. Most of the bass players stand while playing, though sitting is also accepted. The bass guitar is played horizontally across the body just like an electric guitar.

The bass guitar is used in many styles of music including rock, metal, pop, country, blues, and jazz. The electric bass guitar has occasionally been used in contemporary classical music (art music) since the late 1960s. It is used as a solo instrument in jazz, fusion, Latin, funk, and in some rock and heavy metal styles. In India, the bass guitar is now finding increasing use in various up-and-coming rock as well as popular music bands. Western music in India is seen making extensive use of the bass guitar.