(Above picture from http://www.davidbruce.net/images/bansuri.jpg.) A typical bansuri.
The word bansuri comes from the Sanskrit bans "bamboo" and sur "melody" Since many languages are spoken in India the flute naturally goes by different names; it can be called a murali, bansi, baashi, or a baanhi.
The bansuri is one of the most important instruments in Hindu mythology. It was the instrument played by Krishna, who Hindus believe is the eighth reincarnation of the god Vishnu, when he was in child form. Its use in Buddhist paintings can be identified as early as CE 100.
(Above picture from http://upload.wikimedia.org/wikipedia/commons/e/e3/Krishna.jpg. Krishna plays his bansuri. Hindu mythology states that his bansuri had the ability to attract not only women, but even animals!)
The bansuri's use in folk music has a long history. Indian folk music is quite differnt from classical music in its use of fairly crude instruments such as the daf, an Indian tamborine. Folk music is often centured around musical villages and there are many oppurtunities for musicians to hone their skills. The music is practically entirely improvised and there is little or no formal teaching. Almost all possible subjects are covered such as love, devotion. psychology and even anatomy!
(Image from http://www.indianetzone.com/photos_gallery/8/Dollukunitha_2730.jpg. Some Indian folk musicians. Indian folk is usually set to dance.)
The use of the bansuri in classical music has been a surprisingly recent development in the history of Indian development, mainly due to one man: Pannalal Ghosh (1911-1970). Originally a sitarist, he adopted the bansuri at an early age and introduced many of the materials now used in making bansuris today, such as the 32 inch length and the use of seven holes. He was also one of the first to use bamboo. He was instructed by Allauddin Khan (1862?-1972), one of the most famous Indian music teachers of all time, and also had several proteges of his own. Modern bansuri players include Hariprasad Chaurasia (1938--) who is known for his work in film scores.
(Picture from http://pannalalghosh.com/img/pannalalghosh.jpg. Pannalal Ghosh with his bansuri.
Modern bansuris are almost always made out of bamboo. The length is extremely variable, ranging from <12 inches to 40 inches, although 14 (soprano) and 32 (bass) are the most typical lengths. Traditionally, bansuris were made with six holes; nowadays however seven holes are used to make the sound more flexible. Two types of bansuris exist: transverse and fipple. The transverse is used in classical music whereas the fipple is still primarily the domain of folk music.
The timbre of the bansuri is quite a high-pitched and fast sound, although slightly deeper than a Western flute.The sound is also quite breathy, but still remains clear. The sound is fairly cheery. I personally like the sound of the bansuri. For an example of bansuri playing you can watch this video:
This channel also has some good bansuri videos: https://www.youtube.com/user/bansuriflute.
You play the bansuri like a regular flute, by opening and closing holes with your fingers whilst blowing. You can play accidentals-- flats and sharps-- by opening or closing half a hole. Just like with other Indian instruments, the bansuri uses ragas; different patterns of notes based on the time of the day, feeling, etc. Indian music has different names for different finger positions:
Sa-- first, fifth and sixth holes open-- the rest closed;
Komal Re-- the same as Sa, but with the fourth hole half-open;
Shuddha Re-- first, fourth, fifth and sixth holes open, the rest closed;
Pa-- first hole open, rest closed;
Tivra Ma-- all holes except fourth and seventh;
and so on.
There are many positions too numerous to list here. For a more comprehensive list see here: http://chandrakantha.com/articles/indian_music/bansuri_technique.html
(Picture from https://lh6.googleusercontent.com/-rX0tgBULYCg/TWv6P55zrAI/AAAAAAAAAE8/24g3Tk6751k/s640/fingering.gif. A fingering chart for bansuri).
A similar instrument is the venu, also a bamboo flute, which is used in Southern Indian music. It has eight holes and a more monotonous sound. It is also known as the pullankuzhal, the murali, the kulalu, the venuvu or the pillana grovi.
(Picture from http://upload.wikimedia.org/wikipedia/commons/3/30/Venu_or_Pullaanguzhal.jpg.) A venu.