DXing, taken from DX, the telegraphic shorthand for "distance" or "distant", is the hobby of receiving and identifying distant radio or television signals, or making two-way radio contact with distant stations in amateur radio, citizens band radio or other two-way radio communications. Many DXers also attempt to obtain written verifications of reception or contact, sometimes referred to as "QSLs" or "veries".

The practice of DXing arose during the early days of radio broadcasting. Listeners would mail "reception reports" to radio broadcasting stations in hopes of getting a written acknowledgement or a QSL card that served to officially verify they had heard a distant station. Collecting these cards became popular with radio listeners in the 1920s and 1930s, and reception reports were often used by early broadcasters to gauge the effectiveness of their transmissions. Although international shortwave broadcasts are on the decline, DXing remains popular among dedicated shortwave listeners. The pursuit of two-way contact between distant amateur radio operators is also a significant activity within the amateur radio hobby.

Early radio listeners, often using home made crystal sets and long wire antennas, found radio stations few and far between. With the broadcast bands uncrowded, signals of the most powerful stations could be heard over hundreds of miles, but weaker signals required more precise tuning or better receiving gear.

By the 1950s, and continuing through the mid-1970s, many of the most powerful North American "clear channel" stations such as KDKA, WLW, WGY, CKLW, CHUM, WABC, WJR, WLS, WKBW, KFI, KAAY, KSL and a host of border blasters from Mexico pumped out Top 40 music played by popular disc jockeys. As most smaller, local AM radio stations had to sign off at night, the big 50 kW stations were able to reach listeners hundreds of miles away.

The popularity of DXing the medium-wave band has diminished as the popular music formats quickly migrated to the clearer, though less propagating, FM radio beginning in the 1970s. Meanwhile, the MW band in the United States was getting more and more crowded with new stations and existing stations receiving FCC authorization to operate, with low power, at night—this largely peaked in the conservative talk radio boom of the 1990s, and especially since the 2010s, the AM band has gone into decline. In Canada, the decline came sooner as AM stations began moving to FM beginning in the 1980s and continuing through today. A limited number of music stations, including WSM in the United States, CFZM in Canada and—on weekends—WABC still program music on their clear-channel signals.

Outside of the Americas and Australia, most AM radio broadcasting was in the form of synchronous networks of government-operated stations, operating with hundreds, even thousands of kilowatts of power. Still, the lower powered stations and occasional trans-oceanic signal were popular DX targets.

Especially during wartime and times of conflict, reception of international broadcasters, whose signals propagate around the world on the shortwave bands has been popular with both casual listeners and DXing hobbyists.

With the rise in popularity of streaming audio over the internet, many international broadcasters (including the BBC and Voice of America) have cut back on their shortwave broadcasts. Missionary religious broadcasters still make extensive use of shortwave radio to reach less developed countries around the world.