Question

What is the function of the modem?

Answer 1

A modem is the internal or external device its function is to transfer data over communication lines
modems use two different types of data transmission
synchronous and asynchronous
The functions of modem have changed over years it was first used for telegrams and to transmit data in 1950s. 
Modems were used with computers in  1977 for first time to transmit data between computers  firstly it was used for small amount of computers 
As modem improves day by day and were able to transmit information fastly between two or more hosts and the internet network slowly spreads
There are four types of modems ,
1 Fax Modems which solely transfer data between fax machines
2 The traditional ISDN modem
3 the Digital Subscribers Line
4 the Cable Modem

Answer 2

A modem is an external and/or internal device thats function is to transmit digital data over communication lines. Traditional modems used frequently with dial-up networks to change analog data from telephone lines into computer digital data. Broadband modems transfer digital data between digital devices, specifically two.