Why hardware counts in twos
A transistor is a switch: it is either off or on. That is all a chip has to work with, so hardware counts using just two digits, 0 and 1. Each digit is a bit, short for binary digit.
We are used to ten digits, 0 through 9. Binary keeps everything about counting the same and changes only one thing: how many digits a column can hold before it rolls over. Seen next to decimal, binary stops feeling strange.