30 to 50 MHz: This is known as the "VHF low" band. Most transmissions will be in narrow band FM with channels spaced at 20 kHz intervals. A wide variety of stations can be heard on this range, including businesses, federal, state, and local governments, law enforcement agencies, and various industrial radio services.

50 to 54 MHz: This is the six-meter ham radio band. The first megahertz is mainly used for USB, AM, CW, FSK modes, digital modes. The remainder of the band is used for narrow band FM, both simplex and through repeaters. 52.525 MHz is widely used as a simplex and calling frequency.

54 to 72 MHz: Television channels 2, 3, and 4 are located in this range. The video portions will sound like distorted noise on a scanner. The audio portions are in FM, but will sound "clipped" and "tinny" unless your scanner can tune this range in wide band.

72 to 76 MHz: This range is used for remote control signals for model airplanes and garage door openers, wireless microphones (including those used by law enforcement agencies), and two-way communications inside factories, warehouses, and other industrial facilities. Most channels are spaced at 20 kHz intervals.

76 to 88 MHz: This range is used for television channels 5 and 6.

88 to 108 MHz: This is where the FM broadcasting band is located.

108 to 136 MHz: This band is used for civilian aeronautical communications and all transmissions are in AM. Aeronautical beacons occupy 108 to 118 MHz; these continuously transmit a station identification and are used for navigation. The rest of the band is used for traffic between aircraft and air traffic control towers on channels spaced at 25 kHz intervals.

136 to 138 MHz: This segment is mainly used by weather satellites to transmit photographic images. 

138 to 144 MHz: The various military services are the biggest users of this segment in the United States, with most transmissions in narrow band FM and spaced at 5 kHz intervals. You can also hear ham radio operators who are members of the military affiliate radio service (MARS).

144 to 146 MHz: This is the two-meter ham radio band for India. This is the most heavily used ham radio band in the world. USB and various FSK modes are mainly used in the first 500 kHz, and the rest of the band is FM. Most activity is through repeaters, although simplex activity is found on frequencies like 146.52 MHz. This band is extended to 148MHZ in other countries.

148 to 150.8 MHz: The usage here is similar to the 138 to 144 MHz range.

150.8 to 174 MHz: This is known as the "VHF high" band, and it is used by the same wide spectrum of users as the 30 to 50 MHz band.

174 to 216 MHz: This range is used for television channels 7 through 13.

216 to 220 MHz: In the United States, this band is used by the automated maritime telecommunication system (AMTS) used on major inland waterways such as the Great Lakes and the Mississippi river. Communications are in FM on channels spaced at 12.5 kHz intervals. However, the 219 to 220 MHz range is shared with ham radio. On this range, ham stations can be used to relay digital messages to other hams, subject to a maximum power of 50 watts. Hams must first register to use their shared allocation, and cannot use it within range of maritime users.

220 to 222 MHz: This range was reallocated a few years ago from ham radio to land mobile radio. Frequency usage and modulation have not yet been finalized, although new narrow bandwidth modes are expected to be used.

222 to 225 MHz: This is the 1.25-meter ham radio band authorized in many countries but not allowed in India. It is mainly used for FM communication through repeaters, although it is much less heavily used than the two-meter band.

225 to 400 MHz: This very wide band is used for military aviation communications in AM. Most channels are 100 kHz apart.

400 to 406 MHz: This range is used primarily by government and military stations in FM.

406 to 420 MHz: In the United States, this band is used exclusively by the federal government. All transmissions are in FM, with most channels spaced at 25 kHz intervals.

420 to 450 MHz: This is the 70-centimeter ham radio band, second in popularity to the two-meter band on VHF/UHF. The 420 to 444 MHz range is used for USB, digital modes, ham television, and ham communications satellites. The 444 to 450 MHz range is used for FM, mainly in conjunction with repeaters.

450 to 470 MHz: This is the "UHF" band on most scanners, used for many of the same purposes as the 30 to 50 and 150.8 to 174 MHz bands. 

470 to 512 MHz: This is known as the "UHF-T" band, and covers the same frequency range as television channels 14 to 20. This band is used for many of the same purposes as the "UHF" band in areas of the country without television stations on those channels.

512 to 825 MHz: This range is where television channels 21 through 72 are located.

825 to 849 MHz: This range is used for cellular telephone service, with cellular units transmitting here. Listening in this range is prohibited in all countries.

849 to 851 MHz: This band is used to provide telephone service from aircraft in flight. SSB is generally used here. Listening in this range is prohibited.

851 to 866 MHz: This is used by many of the same users as the 450 to 470 MHz band, with channels spaced at 25 kHz intervals.

866 to 869 MHz: This allocation is used by public safety and law enforcement agencies.

869 to 894 MHz: This range is used for cellular telephone service, with cells transmitting here. Listening in this range is prohibited.

894 MHz and above: These higher frequencies are where new communications technologies, such as wireless local area networks, spread spectrum telephony, and direct satellite broadcasting are being implemented.