Do you know how to tell if your lamp is designed for a 1 way or 3 way light bulb?
Both the 3 way and 1 way sockets have the "metal depressed tongue" however,
the 3 way socket has a vertical piece that sticks up while the 1 way socket does not.
Personally I like to have 3 way sockets so I can choose low - med - high lighting depending
on what is going on at our home (lounging/ entertaining/ reading)
3 way socket = Vertical piece on the right (where the arrow is)
If you would like your lamp to be changed to a 3 way socket it can be done by a professional for a few dollars.