Cast Iron is made by, oddly enough, casting iron. A sand mold is made, the molten iron is poured into the mold, the mold is broken off, the article is then finished.
Cast Iron has the advantage, if well made, of being durable, able to hold and distribute heat evenly, and, over a period of time, becoming pretty much non-stick. The non-stick surface is created through a process called seasoning, not to be confused with the seasoning that you do with salt and spices. In the seasoning process, a pan is rubbed inside and out with oil or shortening, then baked in the oven, empty. More oil is added as it gets absorbed. This happens because cast iron is "open" in that it has pores in the metal from the casting process. These get filled with the baked on oil until ultimately, the pan is sealed up by the oil, making it non-stick. This porosity also means that you shouldn't use soap to clean the pans. Soap will remove the surface layer and even get absorbed into the metal itself, giving the potential for a soapy taste to delicate foods cooked subsequently. To clean cast iron, you just rub a warmed pan with salt to loosen everything up, rinse it with warm clear water, dry it on a low stove, then rub it with oil or shortening to seal it up again. Over a period of time and use, the finish on your pan will improve and darken, giving you that great "black iron" look. If you oil lightly after every use, your pan will not rust. If you don't, it will.
The biggest detriment to good cast iron cookware is that it is "heavy". That is intentional. The heavier the piece, the better it holds and distributes heat. Light weight cast iron warps and has hot spots and isn't worth the little bit that it costs. However, if good cast iron pot or pan is full of hot water or oil and you try to move it, the heaviness will make that difficult and/or dangerous. Mine all have double handles, but even so, I let things cool off before I try to move them.
Cast iron has the additional disadvantage of being a reactive metal. This means that if you have an acid in it (tomato sauce or vinegar) the metal will react, darkening the metal AND the food you are cooking, and may change the flavor. However, the iron that comes off of the pan into the food is the same iron that you pay extra bucks for to take as a supplement. Yep, it's good for you. Cast iron cookware can be made non-reactive by coating it in enamel, which is basically glass. Le Creuset is the classic (albeit expensive) example of how this can be done. I'm too cheap to buy Le Creuset, but my local food store had a Tramontina Dutch Oven which looks and cooks like the Le Creuset, but at a much lower price. The Le Creuset lid seals better than the Tramontina, but that wasn't a problem for me. Downside to the enamelware is that it can chip, scratch and stain.
Lodge makes the kind of cast iron that you think of when you think of cast iron cookware. And they've made it easy to use because it comes pre-seasoned. I'm not personally fond of the waxy coat that they provide, but I understand that they needed to remove the mystery of the seasoning process to get people to buy it. For me, it just takes a bit longer to get the pan the way I want it, but it is usable right away.
The best news of all...good cast iron is cheap compared to good aluminum? or multi-clad? pans. And it makes you feel like a pioneer as you use that cast iron griddle to fry your bacon? and make your pancakes?.