Classification of electronic counters：

① Universal counter: can measure frequency, cycle, multi cycle average, time interval, frequency ratio, and accumulation, etc.

② Frequency counter: a counter specifically designed to measure high frequency and microwave frequencies.

③ Calculation counter: A counter with calculation function that can perform mathematical operations and can be controlled by a program to measure, calculate, and display all work processes.

④ Microwave counter: It is a microwave frequency meter composed mainly of a universal counter and a frequency counter, with a frequency extender. Its frequency measurement upper limit has entered the millimeter wave band, with three categories: manual, semi-automatic, and fully automatic. The serialization of microwave counters is an important aspect of the development of electronic counters.