The canonical signed digit, or Non-Adjacent Form (NAF) is a unique way to represent a binary number with a lower absolute hamming weight, using digit € {0,1,-1} as coefficients instead of just digit € {0,1}.

See https://en.wikipedia.org/wiki/Non-adjacent_form

It should improve performance in exponentiation by squaring algorithms and similar as you just need a sub or negate function for -1 cases.
The overall hamming weight W = sum([abs(digit) for digit in bin(int)]) is in average 1/3 instead of 1/2.
Using this representation should lead to improvements in the range of 10-25% for the average case.

An example of this technique can be found in the gnark repo :

definition : https://github.com/ConsenSys/gnark-crypto/blob/8f7ca09273c24ed9465043566906cbecf5dcee91/ecc/bn254/bn254.go#L141-L143
usage (miller loop) : https://github.com/ConsenSys/gnark-crypto/blob/8f7ca09273c24ed9465043566906cbecf5dcee91/ecc/bn254/pairing.go#L161