There was a time when about the only option for a comfortable portable seat in camp was a folding camp stool. They were made of wood and canvas. Viewed from each end they looked like an "X" when open, with canvas stretched between the bars at the top of the "X" to sit on. They're still around too. See Folding Camp Stool and below for a modern example.
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Camp chairs have come a long way since then. Aluminum camp chairs with fiberglass webbing were among the first improvements: light weight and fold flat for easy transport and a back rest and arm rests so you could really relax. In addition to the flat, narrow arms shown on the example they often had wider plastic arms that included a convenient cup holder to keep your favorite beverage out of your lap yet close at hand.
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They were quite comfortable and easy to use. You may still be able to find some around if you like this style. Try ebay. I hung on to a couple of these because they fit nicely in the "rafters" of my motorcycle trailer for transport. They are light weight and make a great place to sit while putting on my riding gear. You can even still get re-webbing kits for them (see re-web kits on amazon.com).
Quad chairs or bag chairs have pretty much taken over the camping scene in recent years. They can be purchased at many stores that carry camping equipment, such as Walmart, often at very reasonable prices. The seats, backs, and armrests are made of cloth.
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They typically fold up into about a 4" square form that fits in a bag. The bags usually have a shoulder strap and/or handle that makes them easy to carry. These chairs may come with and without arms and can include built in snack tables. Many of those with arms, like the one in the picture, have a cup holder built into the arm rest. You can even get recliners, rocking chairs,and cots of similar fold up construction. The canvas material is form-fitting, breathable, and very comfortable.
Both the aluminum folding chairs and "quad" style bag chairs are available in children's sizes too, providing portable, affordable, comfortable seating for the whole family. Some even have built in foldable tables for added convenience.
Camp chairs usually fit easily in the "basement" compartments on motorhomes and travel trailers. You can also get racks that attach to RV ladders that will carry the folding aluminum style chairs. Quad or bag chairs can usually be tucked under a bed, sofa, or dinette or carried in a roof pod or the trunk of a car. For tent campers, quad chairs will usually fit right alongside tents and sleeping bags in your car, truck, or SUV. I have a couple of the vintage folding aluminum camp chairs that fold flat enough to fit into the shallow (1") rafters of my enclosed motorcycle trailer.
Camp chairs are a very good way to enjoy a campfire. They make a good platform to sit on for roasting hotdogs and marshmallows or just relaxing and enjoying the fire. Just make sure you put them away or at least fold them down and lay them flat when you leave the campfire for the night. I've seen several chairs reduced to twisted and melted frames after getting blown into the fire pit after everyone went to bed. Sometimes there's enough heat left in the ground even after the fire is out to damage errant chairs and it only takes a light breeze to blow empty chairs into the fire pit. When they are collapsed and lying on the ground they're a lot less likely to get blown around and into the fire.
Maintenance and repairs. Routine maintenance mostly means keeping them clean and making sure they are properly stored when not in use. The hinge points of folding aluminum chairs might benefit from a bit of lubrication now and then. I would use a Teflon or another dry lube rather than an oily spray that would attract dirt and dust and may soil your clothes. The webbing on some aluminum chairs is attached with screws that might need to be tightened from time to time. Folding aluminum web chairs can be fairly easily re-webbed, if you can still find the webbing kits. That is a good way to repair or refresh vintage chairs, or even change the color to match a "new" RV or tent. Tears in quad chairs can be patched as you would just about any fabric, but they are not really designed to be rebuildable; however anyone who can operate a sewing machine could patch or sew new fabric for these chairs pretty easily. You can probably use the old fabric for a pattern if it isn't too badly worn out. They generally come in a variety of basic colors (red, blue, green, orange, yellow, and black) and sometimes camouflage. If you choose to sew your own, you could make them any color or pattern you like as long as you use an appropriately strong fabric. The factory chairs are usually made of a light weight canvas material. A good quality nylon or polyester might be more stain resistant. Speaking of stains, you might want to consider spraying quad chairs with Scotchguard stain repellant when they're new to help keep them looking good.
If you have room to transport them you might use plastic patio chairs in camp. Probably not very feasible unless you have a very large SUV or a pickup truck or utility trailer to haul them around in! Folding chairs are far more convenient and will usually provide at least the same level of comfort.
Survival camp chairs. You aren't likely to have any camp chairs if you find yourself in wilderness survival mode, but that doesn't mean you have to sit on the ground. You can sometimes find a rock or a stump to sit on or make yourself a rustic stool from just two pieces of wood. It is easiest to make using flat lumber, but that too will probably not be an option in survival mode. The basic design is a "T". You sit on the cross bar of the "T" and the leg supports your weight. If you have to make a stool from limbs you'll probably want to notch the cross bar so it doesn't roll off. Since you have to balance this one-legged stool it may take a little practice, but it sure beats sitting on cold, wet, muddy, or snowy ground. Of course, if you're handy with lashing, you can make a 3-legged camp stool or even a real camp chair from small branches and cordage.
Camp chair accessories. One of the most popular accessories are umbrellas that clamp to the chair frame to provide shade and protection from light rain. Another rather esoteric option is called "Backglo". It is a reflective shield that attaches to the back of the chair and extends all the way to the ground below to reflect heat from the campfire onto your back while blocking any breeze back there. Lap trays or snack tables can be used with many camp chairs. There are also little folding tables available in the quad chair style that can be used as tables or as foot stools. They look like a quad chair without a back.
Camp chairs are not usually used on boats, but they could be if the need came up. Deck space on most boats is limited and there is usually sufficient and appropriate seating seating built in. The almost constant movement of a boat makes loose chairs impractical. If you need to use camp chairs on a boat make sure the feet aren't going to damage the deck. Missing plastic caps or sharp edges could cause significant damage to deck surfaces. Aluminum chairs with U-shaped legs distribute the weight and avoid that problem. You might want to carry camp chairs on your boat if you stop on shore overnight or just for meals and other activities -- if you have room for them on board.
Sittin' pretty!