Autograd
Also: automatic differentiation, autodiff
The machinery that records every operation as it runs and then walks that record backwards to produce gradients, so nobody has to derive derivatives by hand.
What people get wrong
It is neither symbolic differentiation nor a numerical approximation. It computes exact derivatives, numerically, by composing the known derivative of each primitive operation.
A definition is not an understanding. This is taught properly in Automatic differentiation from scratch, part of Backpropagation.
Learn this properlyTerms from the same topic