A wide variety of amateur radio contests are sponsored every year. Contest sponsors have crafted competitive events that serve to promote a variety of interests and appeal to diverse audiences. Radio contests typically take place on weekends or local weeknight evenings, and can last from a few hours to forty-eight hours in duration. The rules of each contest will specify which stations are eligible for participation, the radio frequency bands on which they may operate, the communications modes they may employ, which other amateur radio stations they may contact, and the specific time period during which they may make contacts for the contest.

Some contests restrict participation to stations in a particular geographic area, such as a continent or country. Contests like the European HF Championship aim to foster competition between stations located in one particular part of the world, specifically Europe. There are contests in which any amateur radio station worldwide may participate and make contact with any other stations for contest credit. The CQ World Wide DX Contest permits stations to contact other stations anywhere else on the planet, and attracts tens of thousands of participating stations each year. In large contests the number of people taking part is a significant percentage of radio amateurs active on the HF bands, although they in themselves are a small percentage of the total amateurs in the world.

There are regional contests that invite all stations around the world to participate, but restrict which stations each competitor may contact. For example, Japanese stations in the Japan International DX Contest (sponsored by Five Nine magazine) may only contact other stations located outside Japan and vice versa. There are also contests that limit participation to just the stations located in a particular continent or country, even though those stations may work any other station for points.

All contests use one or more amateur radio bands on which competing stations may make two-way contacts. HF contests use one or more of the 160 meter, 80 Meter, 40 Meter, 20 Meter, 15 Meter, and 10 Meter bands. VHF contests use all the amateur radio bands above 50 MHz. Some contests permit activity on all HF or all VHF bands, and may offer points for contacts and multipliers on each band. Other contests may permit activity on all bands but restrict stations to making only one contact with each other station, regardless of band, or may limit multipliers to once per contest instead of once per band. Most VHF contests in North America are similar to the ARRL June VHF QSO Party, and allow contacts on all the amateur radio bands 50 MHz or higher in frequency. Most VHF contests in the United Kingdom, however, are restricted to one amateur radio band at a time. An HF contest with worldwide participation that restricts all contest activity to just one band is the ARRL 10 Meter Contest.

Contests exist for enthusiasts of all modes. Some contests are restricted to just CW emissions using the Morse code for communications, some are restricted to telephony modes and spoken communications, and some employ digital emissions modes such as RTTY or PSK31. Many popular contests are offered on two separate weekends, one for CW and one for telephony, with all the same rules. The CQ World Wide WPX Contest, for example, is held as a phone-only competition one weekend in March, and a CW-only competition one weekend in May. Some contests, especially those restricted to a single radio frequency band, allow the competing stations to use several different emissions modes. VHF contests typically permit any mode of emission, including some specialty digital modes designed specifically for use on those bands. As with the other variations in contest rules and participation structure, some contest stations and operators choose to specialize in contests on certain modes and may not participate seriously in contests on other modes. Large, worldwide contests on the HF bands can be scheduled for up to forty-eight hours in duration. Typically, these large worldwide contests run from 0000 UTC on Saturday morning until 2359 UTC Sunday evening. Regional and smaller contests often are scheduled for a shorter duration, with twenty-four, twelve, and four hours being common variations.

Many contests employ a concept of “off time” in which a station may operate only a portion of the available time. For example, the ARRL November Sweepstakes is thirty hours long, but each station may be on the air for no more than twenty-four hours. The off-time requirement forces competitive stations to decide when to be on the air making contacts and when to be off the air, and adds a significant element of strategy to the competition. Although common in the 1930s, only a small number of contests today take place over multiple weekends. These competitions are called “cumulative” contests, and are generally limited to the microwave frequency bands. Short “sprint” contests lasting only a few hours have been popular among contesters that prefer a fast-paced environment, or who cannot devote an entire weekend to a radio contest. A unique feature of the North American Sprint contest is that the operator is required to change frequency after every other contact, introducing another operational skills challenge. Whatever the length of the contest, the top operators are frequently those that can best maintain focus on the tasks of contest operating throughout the event.

Some contests, such as the Maine 2 Meter FM Simplex Challenge sponsored by the Wireless Society of Southern Maine, offer newly licensed hams the ability to take part in contesting for the first time, by restricting contacts to a single VHF band, and providing entry categories for anything from a handheld radio to a fully equipped contest station.

The wide variety of contests attracts a large variety of contesters and contest stations. The rules and structure of a particular contest can determine the strategies used by competitors to maximize the number of contacts made and multipliers earned. Some stations and operators specialize in certain contests, and either rarely operate in others, or compete in them with less seriousness. As with other sports, contest rules evolve over time, and rule changes are one of the primary sources of controversy in the sport.