Q.Give a broad classification of counters.

A counter is a sequential circuit made of flip-flops that counts the number of clock (input) pulses. Broadly, counters are classified by how the flip-flops are clocked. …

[!TLDR]

Counters are broadly of two kinds: asynchronous (ripple/serial) counters and synchronous (parallel) counters, distinguished by whether all flip-flops are clocked together.

A counter is a sequential logic circuit — a set of flip-flops whose state changes in response to the pulses applied at its input — used to count those pulses. The broad classification is based on the way the clock reaches the flip-flops.

Asynchronous (ripple / serial) counters: the flip-flops are not all triggered at the same instant. Only the first flip-flop receives the external clock; each subsequent flip-flop is clocked by the output of the previous one, so the count "ripples" through the stages. This makes them simple to build but slower, because the propagation delays of the individual flip-flops add up. …