Why is there an implied (or hidden) bit in IEEE floating point format? What is the purpose of it? It is mentioned in passing on Wikipedia.
From (Complete) Tutorial to Understand IEEE Floating-Point Errors:
"[Fraction] is the normalized fractional part of the number, normalized because the exponent is adjusted so that the leading bit is always a 1. This way, it does not have to be stored, and you get one more bit of precision. This is why there is an implied bit."
It basically allows for higher precision.