From the ARRL website
What’s is the Appeal of Ham Radio?
Amateur Radio operators come from all walks of life — doctors, students, kids, politicians, truck drivers, movie stars, missionaries and even your average neighbor next door. They are of all ages, sexes, income levels and nationalities. Whether through Morse Code on an old brass telegraph key, voice communication on a hand-held radio or computerized messages transmitted via satellite, all hams use radio to reach out to the world.
You can communicate from the top of a mountain, your home or behind the wheel of your car, all without relying on the Internet or a cell phone network You can take radio wherever you go! In times of disaster, when regular communications channels fail, hams can swing into action assisting emergency communications efforts and working with public service agencies. For instance, the Amateur Radio Service kept New York City agencies in touch with each other after their command center was destroyed during the 9/11 tragedy. Ham radio also came to the rescue during Hurricane Katrina, where all other communications failed, and the devastating flooding in Colorado in 2013.
You can communicate with other hams using your voice and a microphone, interface a radio with your computer or tablet to send data, text or images, or Morse code, which remains incredibly popular. You can even talk to astronauts aboard the International Space Station, talk to other hams through one of several satellites in space, or bounce signals off the moon and back to Earth!
Some hams like to build and experiment with electronics. Computer hobbyists enjoy using Amateur Radio’s digital communications opportunities. Others compete in “DX contests,” where the object is to see how many hams in distant locations they can contact. Mostly we use ham radio to form friendships over the air or through participation in one of more than 2000 Amateur Radio clubs throughout the country. There are over 600,000 radio amateurs in the United States and over 2,000,000 worldwide.
Look at the dial on an old AM radio and you’ll see frequencies marked from 535 to 1605 kilohertz. This is one radio “band.” There are other bands of radio spectrum for amateur, government, military and commercial radio uses. If you could hear the many different bands, you would find aircraft, ship, fire and police communication, as well as “shortwave” stations, which are worldwide commercial and government broadcast stations from the U.S. and abroad. Amateurs are allocated 26 bands (i.e., specific groups of frequencies) spaced from 1.8 Megahertz, which is just above the broadcast radio frequencies, all the way up to 275 Gigahertz! Depending on which band we use, we can talk across town, around the world or out to satellites in space. Hams can even bounce signals off the moon!
List of practice examine sites: