Hams operate on several frequency bands. Following are the major ham bands from lowest frequency to highest along with other common bands to provide perspective::

Wavelength Range Frequencies Characteristics
AM broadcast band LF 0.540-1.700 Mhz  
160 meters HF 1.800-2.000 Mhz Very long antennas required
80 meters HF 3.500-4.000 Mhz. Moderate distance nightime band. Long antennas required.
40 meters HF 7.000-7.300 Mhz Moderate distance day, long distance night
30 meters HF 10.100-10.150 Mhz CW only band. Long distance. A WARC band.
20 meters HF 14.000-14.350 Mhz. The premier long distance (DX) band
17 meters HF 18.068-18168 Mhz. A WARC band
15 meters HF 21.000-21.450 Mhz Long distance when conditions are good
12 meters HF 24.890-24.990 Mhz A WARC band
Citizens Band HF 26.965-27.405 Mhz Line of sight. Also referred to as 11 meters.
10 meters HF 28.000-29.700 Mhz Long distance when conditions are good. A few FM repeaters.
6 meters VHF 50.000-54.000 Mhz Short range. Mostly line of sight, but frequent middle and long distance openings occur. A few repeaters.
FM broadcast band VHF 88.000-108.000 Mhz.  
Aviation Band VHF 108.000-137.000 Mhz  
2 meters VHF 144.000-148.000 Mhz Short range. Line of sight. Most used VHF band. More FM repeaters than any other band.
1.25 meters UHF 222.000-225.000 Mhz Short range. Line of sight. Not heavily used.
70 centimeters UHF 420.000-450.000 Mhz Short range. Line of sight. Commonly used UHF Band. Many FM repeaters.

Mobile Operation

Most mobile operations are on 2 meters and 70 centimeters using the FM mode. On HF there is some mobile on most bands other than 160 meters where antennas are impractical. The most common mobile HF bands are 20 and 40 meters, and the most commonmode is SSB.

Ham Modes

CW Continuous Wave. Morse code. Mainly HF
SSB Single sideband. Voice. Mainly HF
AM Amplitude Modulation. Voice Rare
FM Frequency Modulation. Voice Mainly VHF and UHF using repeaters.

For details see the ARRL frequency and mode chart.