Why does the number four at bottom of a time signature mean crochet notes?

In a time signature, the bottom number indicates the type of note that receives one beat. In the case of a "4" at the bottom of a time signature, it signifies that a quarter note (also known as a croche) gets one beat. Therefore, in 4/4 time, for example, there are four beats per measure, with each beat represented by a quarter note. This standardization helps musicians understand the rhythmic structure of a piece.