The allocation of amateur radio frequencies is accomplished internationally by the International Telecommunications Union (ITU). ITU oversees how much radio spectrum is allocated to amateur radios transmissions just as it allocates radio spectrum to all governments worldwide. Individual amateur stations are free to use any frequency within the authorized frequency ranges called bands. A band starts at one particular frequency and extends to another which is the end of the band. An amateur radio operator can talk on any of the frequencies in this range of frequencies and is not limited to channels like other radio services. There are band plans that dictate what types of transmissions are allowed in different segments of each band.
A link to the current Amateur Radio frequency/band chart is below::
A link to the current ARRL band plan is below::