Does The Modem You Use Affect The Speed Of Your Internet?

Actually The speed of Internet Depends on two things
Modem(obviously)
and your ISP should have a dedicated internet lines

about modem yes it ultimately depends upon your modem what speed you'll get, I don't think the thing is expensivelyness, you should get a modem which supports speed higher than 56MBPS

And if you are having the speed in MBPS what is slow in it
maybe you should have a speedtest here

If you are getting 20MBPS or more than that it's sufficient, you did not need a new modem, although you may get one

Hope it hELPS!!!

No.  it is not your modem that increases speed it is the way it is provided to your modem via cable (broadband) or telephone (slow)

What really matter is the speed of the modem not the modem manufacturer. The maximum speed of a modem is 56 kbps. The second thing which then matters is the speed provided by your ISP. You may have 56kbps modem but your ISP might be giving you only 35kbps. This way your internet speed will be low.