In addition to what David and lesleypaulvj have said below I want to emphasize that this hobby, perhaps more than others, is almost limitless in its scope of activities. Most people think of ham radio as just talking on a microphone to other hams at great distances, but it is much, much more than that. Here's just a small sample of what hams do:
- send images, e-mail, text via radio
- attempt to communicate with very low power (if under 5 watts we call it QRP, if under 1 watt QRPp). People can communicate thousands of miles with less power than in a flashlight.
- Experiment with new circuits, antennas, etc. in order to advance the state of the art of the hobby.
- Participate in contests, locally, regionally, or worldwide. Some are quite competitive and require top skills and equipment to get a high score
- Provide communications during disasters when nothing else is working
- Help others come into the hobby and organize to administer tests for new licenses
- Learn Morse Code, one of my favorite modes, by the way.
- Build their own equipment and antennas
- Activate far away places, such as remote islands where there are no hams, so that other hams can add to their list of countries (entities) they have communicated with. This is called DXing.
The list goes on and on. 73!