A tunnel tent uses two or more parallel hoop-shaped poles to create a long, tunnel-like shelter with excellent interior space and weight efficiency. It is not freestanding — it must be staked out under tension — and is strongest when its low end faces into the wind, making orientation and good anchors important.
A dome tent is the classic tent design in which two (or more) poles cross over the top to form a self-supporting dome. It's freestanding, stable in wind from all directions, and quick to pitch, making it the most popular backpacking and family tent shape, with good headroom near the center.
A four-season tent is built to withstand winter and alpine conditions — heavy snow loads, strong winds, and cold — with more and stronger poles, sturdier fabric, and less mesh than a three-season tent. The trade-offs are more weight and less ventilation, so it's overkill for mild-weather camping.
A three-season tent is built for spring, summer, and fall — the most common type — balancing low weight, good ventilation (lots of mesh), and the ability to handle rain and moderate wind. It is not made for heavy snow loads or severe winter storms, which call for a sturdier four-season tent.
A single-wall tent uses one layer — a waterproof (often waterproof-breathable) fabric — instead of a separate inner and rainfly, to cut weight and bulk. It's popular for ultralight backpacking and mountaineering, but with no air gap it's more prone to interior condensation, requiring good ventilation and management.
A double-wall tent has two layers: a breathable (often mesh) inner tent and a separate waterproof rainfly over it. The gap between them lets interior moisture escape while the fly sheds rain, which greatly reduces condensation dripping on you. It's the most common, comfortable design, though heavier than a single-wall tent.
A freestanding tent holds its shape on its own pole structure without needing stakes or guylines, so you can pick it up and move it fully pitched. This makes it easy and forgiving to set up on any surface, including rock and hard ground, at the cost of a bit more pole weight than minimalist non-freestanding shelters.
Water treatment is the general practice of making backcountry water safe to drink by removing or killing pathogens, through filtering, purifying (UV or chemical), or boiling. Untreated wild water can carry Giardia, bacteria, and sometimes viruses, so treating all drinking water is a core backcountry health habit.
Water purification is treating backcountry water to remove or kill all pathogens — including the viruses that filters miss — using methods like UV light, chemical drops or tablets, or boiling. 'Purifier' implies virus protection, unlike a basic filter. The right method depends on the water source, region, and how clear the water is.
A water filter removes bacteria, protozoa (like Giardia and Cryptosporidium), and sediment from backcountry water by physically straining it through a fine membrane or element. It makes natural water safe to drink in most of North America, but most filters don't remove viruses, so where viral contamination is a risk a purifier or chemical treatment is needed.