Type a number to see the bits a computer really stores: a sign, an exponent and a mantissa. Flip any bit, step to the neighbouring float, and measure exactly how far the stored value sits from the one you typed. New to bits? Start with the Bitwise lab.
Whatever you type is rounded to the nearest float. Click any bit to flip it and the decimal follows. Sign, exponent and mantissa are coloured separately.
The same pattern, decoded field by field. A float is a sign, a power of two and a significand multiplied together, and every value it can hold is an exact binary fraction.