G code (G-code, also known as RS-274) is the most widely used numerical control  programming language. There are multiple versions and it is mainly used to control automatic machine tools in computer-aided manufacturing. G code is sometimes called G programming language.
G codes are instructions in CNC programs. Generally referred to as the G command. Use G code to realize fast positioning, reverse circular interpolation, forward circular interpolation, intermediate point circular interpolation, radius programming, and jump processing.

Code name-brief description of function
G00——Quick positioning
G01——Linear interpolation
G02——clockwise circular interpolation
G03——Counterclockwise circular interpolation
G04——Timed pause
G05——-arc interpolation through the intermediate point
G06——parabolic interpolation
G07——Z spline curve interpolation
G08——Feed acceleration
G09——Feed deceleration
G10——Data setting

G16——Polar coordinate programming
G17——Processing XY plane
G18——Processing XZ plane
G19——Processing YZ plane
G20——Inch size (Franken system)
G21—–Metric size (Franken system)
G22——Radius dimension programming method
G220—–Use on the system operation interface
G23——diameter size programming method
G230—–Use on the system operation interface
G24——End of subroutine
G25——Jump processing
G26——Cycle processing
G30——Magnification cancellation

G31——-rate definition
G32——Equal pitch thread cutting, inch system
G33——Equal pitch thread cutting, metric system
G34——increased pitch thread cutting
G35—— thread cutting with reduced pitch
G40——Tool compensation/tool offset cancellation
G41——tool compensation-left
G42——tool compensation-right
G43——tool offset-positive
G44——tool offset-negative
G45——tool offset+/+
G46——tool offset +/-
G47——tool offset-/-
G48——tool offset-/+
G49——tool offset 0/+

G50——tool offset 0/-
G51——Tool offset +/0
G52——tool offset-/0
G53——Straight line offset, logout
G54——Straight line offset x
G55——Straight line offset y
G56——Straight line offset z
G57——Straight line offset xy
G58——Straight line offset xz
G59——Straight line offset yz
G60——accurate path method (fine)
G61——accurate path method (middle)
G62——accurate path method (coarse)
G63——Tapping thread
G68——tool offset, internal angle
G69——Tool offset, external angle
G70——Inch size inch (this one is from Siemens, and the one from Frank is G20)

G71——Metric size mm
G74——Return to reference point (machine zero point)
G75——Return to the zero point of programmed coordinates
G76——-threading compound cycle
G80——canned cycle logout
G81——External canned cycle
G331—–Thread canned cycle
G90——absolute size
G91—— relative size
G92——Prefabricated coordinates
G93——time countdown, feed rate
G94——Feed rate, feed per minute
G95——feed rate, feed per revolution
G96——Constant linear speed control
G97——Cancel constant line speed control