General MIDI is a set of rules within the MIDI specification that has been developed with the hobbyist and casual user in mind. It establishes a classification of instruments, appropriately enough known as General MIDI instruments, which subscribe to a minimum set of operating standards and which also standardize the way their sounds are organized. For example, all General MIDI instruments provide an acoustic piano sound in patch #0 and a fretless bass sound in patch #36, etc. In addition, these instruments standardize their drum key map organization and always use MIDI channel 10 for the reception of drum sounds. There are many MIDI sequence files available commercially and in the public domain which have been created specifically for these kinds of instruments. Most sound cards follow the General MIDI standard (at least loosely) and there are also a number of high quality but inexpensive General MIDI instruments on the market.