Question

What is modem explain in points

Answer 1

combined device

for modulation and demodulation

Answer 2

A modem is a device or program that enables a computer to transmit data over,

for example, telephone or cable lines. Computer information is stored digitally,

whereas information transmitted over telephone lines is transmitted in the form of analog waves.

A modem converts between these two forms.

depends what you mean exactly by modems.

The original modems modulated the digital signal onto the audio signal of your telephone. ...

So they are sort of the same of the classic modem, but also different.

Old modems probably have occasional uses where the telephone lines are still the classic original audio systems.