What is counter and register in electronics?

Counter is a digital circuit which is able to count from a specific number to another specific number (according to the requirement). Depending upon the counting style the counters can be divided into two.

i) UP counter- which increment one by one (eg. 0,1,,2,3,4,5............15) for a 4 bit counter

ii) Down counter- which decrements one by one (eg. 15,14,13,12,11,10,9,8................0) for a 4 bit counter.

A simple apllication of a counter is a diigital clock, having 3 counters. One for counting the seconds, another for counting the minute and the last one for counting the hour.