An amateur radio operator is someone who uses equipment at an amateur radio station to engage in two-way personal communications with other amateur operators on radio frequencies assigned to the amateur radio service. Amateur radio operators have been granted an amateur radio license by a governmental regulatory authority after passing an examination on applicable regulations, electronics, radio theory, and radio operation. As a component of their license, amateur radio operators are assigned a call sign that they use to identify themselves during communication. There are about three million amateur radio operators worldwide.
Amateur radio operators are also known as radio amateurs or hams. The term "ham" as a nickname for amateur radio operators originated in a pejorative usage (like "ham actor") by operators in commercial and professional radio communities. The word was subsequently adopted by amateur radio operators.
Few governments maintain detailed demographic statistics of their amateur radio operator populations, aside from recording the total number of licensed operators. The majority of amateur radio operators worldwide reside in Japan, the United States, Thailand, South Korea, and the nations of Europe. The top five countries by percentage of the population are Japan, Slovenia, Taiwan, South Korea and Thailand. Only the governments of Yemen and North Korea currently prohibit their citizens from becoming amateur radio operators. In some countries, acquiring an amateur radio license is difficult because of the bureaucratic processes or fees that place access to a license out of reach for most citizens. Most nations permit foreign nationals to earn an amateur radio license, but very few amateur radio operators are licensed in multiple countries.