The LM386 is an integrated circuit

Integrated circuit

An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...

 consisting of a low voltage audio power amplifier. It is suitable for battery-powered devices such as radios, guitar amplifiers, and hobbyist projects. The IC consists of an 8 pin dual in-line package (DIP-8) and can output 0.5 watts power using a 9-volt power supply.

Models

There are different models of the LM386 that have slightly different specifications, outlined below.

Chip Name	Min Voltage	Max Voltage	Minimum Output Power	Typical Output Power
LM386N-1	4 Volts	12 Volts	250 mW	325 mW
LM386N-3	4 Volts	12 Volts	500 mW	700 mW
LM386N-4	5 Volts	18 Volts	700 mW	1000 mW

Guitar amplifier usage

• The well-known "Smokey Amp" created by Bruce Zinky
  Bruce Zinky
  Bruce Zinky is an American Electronic Engineer based in Flagstaff, ArizonaAfter graduating from Chico State University, he headed the Fender amplifier "custom shop" in the early 1990s, helping to return Fender to the forefront of quality professional instrument amplifier manufacturers...
  
   uses an LM386 and is notable for being able to fit in a cigarette package
• The "Little Gem" and "Little Gem MkII" are modified/cloned versions of the "Smokey Amp".
• The "Ruby" amp is a modified version of a Little Gem amplifier.
• The Marshall
  Marshall Amplification
  Marshall Amplification is a British company, founded by drummer Jim Marshall, that designs and manufactures music amplifiers, brands personal headphones/earphones , and, after acquiring Natal Drums, drums and bongos. Marshall amplifiers, and specifically their guitar amplifiers, are among the most...
  
   MS-2 and MS-4 miniature practice amps use a single-in-line packaged NJM386 manufactured by JRC.
• The LM386 is one of the most common amps used in DIY guitar preamps and sustainers due to its ability to run on a single 9v battery.