Summary:
What to look for in a backpacking tent.
Tent Weight and Size
The qualities desirable in a backpacking tent are different from those tents being pitched next to a car in a campground. The biggest difference being that the backpacking tent will be carried with you and therefore, should be small and lightweight. Most modern two person tents weight around four to five lbs. whereas a roomy family camping tent can weigh twenty lbs or more. Solo or single person tents can weigh less than three lbs and are great if you are hiking alone. However, if you are hiking with someone else, it usually works out better weight wise to split the gear and take a two person tent.
Tent Quality
The quality of the tent is more important when backpacking because there is usually nowhere dry to go if the tent starts leaking. While a top quality tent is not necessary, cheap discount store tents should only be used if the forecast calls for clear weather.
Being tired, wet, and cold knowing the next dry place is at least ten miles away on a rocky trail will quickly put a damper on what should be an enjoyable outdoor experience.
Clips and Sleeves
There are two common ways that tent poles are attached to the tent. One is using sleeves that the poles slide through and the other is using clips that latch over the poles. Some tents even use a combination of clips and sleeves. In general, clip based designs are easier and faster to set up, while sleeve based designs are stronger and can be easily repaired with a needle and thread right at the camp site. For most conditions, I believe the clips are plenty strong and are generally better because of how quickly they allow the tent to be set up and dismantled.
Free Standing and Staked Designs
Free standing tents seem to have become the norm. Their primary advantage is that they can be set up without being staked into the ground. Stakes are still important to keep the tent from blowing around, but the stakes usually do not need to be driven far into the ground. Staked tents tend to be a bit lighter than free standing tents, but need to be staked solidly into the ground to hold their shape. Staked tents can be difficult to set up or keep up if the soil is hard or rocky. I've become a convert from staked tents to freestanding tents after bending multiple tent pegs beyond repair trying to pitch the tent on hard rocky ground.
Single Wall and Double Wall Construction
Double wall tents are tents that require a separate rain fly to keep out water. Although they are slightly heavier than their single walled counterparts and take a bit longer to set up, they are generally less expensive, warmer, and hold up better in wet conditions. While the lower weight specifications and small packing size of the single wall tents make them attractive, the double wall tents are generally a better deal economically.
Three Season and Four Season Specifications
Three season tents are just that; tents designed for Spring, Summer, and Fall camping. Few people go backpacking in the winter compared to the other three seasons, so the vast majority of tents sold are three season tents. Four season tents are built from heavier materials in order to hold up against the winter weather and are bulkier and harder to carry. Some manufacturers offer a 3+ season tent if you are camping early in the Spring or late in the Fall; but unless you are planning specifically to camp in the winter months a three season tent is more than sufficient without undue bulk and weight.
Vestibules
If you don't have room to keep your shoes in the tent with you, vestibules are a great place to keep them dry and yet outside the main tent. Some vestibules provide enough of an overhang to allow the screen or even the door to be open during the rain. I personally enjoy feeling the breeze from a storm while I am dry inside the tent. Most people probably would not consider the vestibule worth the weight, but they are a nice luxury.
Conclusions
While different individuals will select different tents based on various factors, understanding the fundamentals differences between tents can help you pick the tent design that fits your hiking style and conditions.