My wife and I are both heavily involved with Search and Rescue - we use what's called commercial frequencies (aka race radio) channels for that. CBs don't have the range of HAM. You do need a license for HAM, those guys in the basement get all persnickety if they think you don't have a license and will call the feds who will come to your doorstep... but it's really an easy test.
HAM is a number of frequencies that are reserved for amateur radio use. There are 3 levels, technician, general, and extra licenses. With each succeeding level, you can use more exclusive frequencies. Technicians can use 144mhz, 220mhz, and 440 mhz - those are normally described by the length of the wave that each one does. For example, the lowest is 70cm between peaks, technicians can use that frequency and 2m, and 6m. the longer the distance between the peaks the greater the range (sort of). the Extra license lets you use 10 m - but at those frequencies you can do serious harm (think microwave your neighbor) - so there is the basic. To confuse you just a bit more, CB uses 11m, but it doesn't allow the power - 3 watts is legal, 5 watts you won't usually get in trouble. With HAM radios and license, we can broadcast 50 watts. More watts, more power, more range. Not just that, but we can use parallel frequencies so that we can talk over each other if needed. Best of all, if you're using a private repeater, you can make it impossible for anyone but you to use that repeater by using offsets and other methods of gatekeeping.
HAM has been around since before WW2, but it's something that allow for transmitting even if the other forms of communication fail. A properly set up radio can bounce its signal off the atmosphere and talk to the other side of the world.... try with your cell phone when the power is out... because of its resiliency, the government (most governments, actually, have a vested interest in keeping the method alive). Because of that, and because we haven't talked yet about repeaters - that's a pretty cool thing. When you have a General license, you can set up your own repeater. Because there are thousands of people who set up repeaters, you can talk from just about anywhere using those 'public' repeaters. Best of all, outside of the equipment cost (which has dropped dramatically with chinese radios) - you can talk for free to pretty much anywhere in the world.
Now your CB question. Some radios (like the TYT 9800 in my Suburban and Land Cruiser) have the ability to broadcast on Technician frequencies, and Commercial frequencies (which are owned and you must have permission to use). In addition, it can also be a repeater and broadcast on CB, FRS and GMRS frequencies. If you use it for just those frequencies, you don't need a license... but it's not that hard to get, so why not? some of the most fun is listening in on those frequencies. Most NASCAR teams use Commercial frequencies and you can get the unadulterated news from the pits via listening. Cops broadcast on 440, and 880 frequencies - which you can, for the most part, listen in on. When the power goes out, I can listen to PSE's crews as they work their way to restoring power....
oh yeah, and I can talk to friends 5 miles away on the back side of another mountain without static.... which is really helpful when you're herding a bunch of cats over Liberty during the Overland Rally...
But in an emergency - it could be your only phone line, and could get you help in pretty remote places - think Africa or Saskatchewan.