Hamming distance

In telecommunication, the Hamming distance or signal distance is the number of digit positions in which the corresponding digits of two binary words of the same length are different.

It corresponds to the weight (number of ones) in the XOR of the words, or to the Manhattan distance between two vertices in an n-dimensional hypercube (where n is the length of the words).

For instance, the Hamming distance between 1011101 and 1001001 is two.

The concept can be generalized to other notation systems. For example, the Hamming distance between 2143896 and 2233796 is three, and between "toned" and "roses" it is also three.

Source: from Federal Standard 1037C