Amateur radio, also known as ham radio, is NOT the same thing as CB, or Citizens Band, radio. It is an entirely different radio service (the Federal Communications Commission refers to the various types of radio communication activities it regulates as "services"). The Citizens Band Radio Service uses low-power transmitters, operating on 40 channels in the 27 MHz range (some radios claim to have as many as 120 channels). CB radios must be of a design certified by the FCC, and cannot be modified. You do not need a license to operate a CB radio. There is no requirement to identify CB transmissions, although many CBers use a name of their own choosing, called a "handle", to identify themselves on the air. CB radios typically have a range of several miles, although atmospheric conditions can carry a signal much farther. The FCC rules limit communications to 250 kilometers (155.3 miles).
As I explained on my ham radio web page, the Amateur Radio Service requires a license that is earned by passing one or more examinations. Amateur radio operators have great flexibility in their activities, and many frequency bands on which to operate. Hams communicate locally or globally. Amateur radio transmissions must be identified, using call signs issued by the FCC.
Note on punctuation: It seems like the word "citizens" in Citizens Band should have an apostrophe in it. I do not know the history as to why the name was chosen, but I do know that on the FCC web site, as well as in the Code of Federal Regulations (47 CFR 95 Subpart D), Citizens Band has no apostrophe.