For this sign representation method, the leftmost bit (most significant bit) denotes whether the value is negative (0 for positive or zero, 1 for negative).
Those values can be taken into account by subsequent branch or arithmetic commands.
The C programming language, along with its derivatives, implements a signedness for all integer data types, as well as for "character".
Compilers often issue a warning when comparisons are made between signed and unsigned numbers or when one is cast to the other.
These are potentially dangerous operations as the ranges of the signed and unsigned types are different.