Binary numbers are a base-2 numbering system, which means they use only two digits - 0 and 1 - to represent numbers. In the binary system, each digit position represents a power of 2, starting with 2^0 at the rightmost position and increasing by a power of 2 as you move to the left. For example, the binary number 1011 represents (1 x 2^3) + (0 x 2^2) + (1 x 2^1) + (1 x 2^0), which equals 11 in decimal form. Binary numbers are commonly used in computer programming and digital electronics because they can be easily represented by electronic switches that are either on (1) or off (0).