A survival knife, also sometimes named a bushcraft knife, can be utilized for wilderness tasks like cutting rope, whittling wood, cutting tree branches, excavating, and even processing game. Its multipurpose nature is rather important to woodsmen who don't want to be weighed down by a bunch of heavy tools.
Bushcraft Knives vs. Survival Knives
The words bushcraft knife and survival knife mean the same thing. Some state a bushcraft knife is created for a situation where the owner has intentionally set out to accomplish outdoor tasks, whereas a survival knife is created for more of an surprise, emergency situation. In reality, however, this distinction is basically nonexistent and most manufacturers do not distinguish between the two.
Further complicating matters is that these blades are also frequently referred to as "wilderness" blades or "camping" blades.
"Batoning" is one process that survival blades accomplish well but bushcraft blades do not. Batoning is to apply the knife to chop away larger tree limbs. A person puts the knife atop the wood and slams it into the branch by hammering on the knife's spine.
Blades
Bushcraft knife blades typically be about four inches long. Outdoorsmen with a bigger hand might prefer a lengthier blade, though a blade in excess of than five inches is not recommended.
When searching for a high caliber knife, search for one that features a full tang or hidden tang. A full-tang blade covers the entire length and width of the knife. It is usually visible on the edge of the handle. A hidden tang knife traces the entire length of the knife as well, however it is tapered when it is inside the handle. It is also entirely covered by the handle.
Steel can consist of stainless steel or carbon steel. Stainless steel will not oxidize, a big advantage in exposure to moisture. Carbon steel blades are easier to re-sharpen and should maintain a sharper edge.
Edges can be serrated or non-serrated. Full-serrated blades are not recommended as they are difficult to sharpen, but many blades will have a small piece of the blade that is serrated while the majority of the edge is non-serrated.
A2 and VG-10 are widely-available, top-of-the-line carbon steels, while 440C and AUS8 are popular quality stainless steels.
Handles
When shopping for a survival knife, you'll want something that you can clutch easily no matter what the weather is like. Best options include rugged materials like micarta or stag bone. You may also wish to consider stacked leather, though only if you're not going to use it in consistently rainy conditions.
These sorts of knives typically don't sport a finger guard. This is because they were not designed to be used with a sawing movement, but instead for of the vertical movement of cutting.
It's possible to hide undersized things in the knife if it has a hollow handle with a removable lid, such as waterproof matches. This kind of construction makes the handle less durable, though, so is not a good choice.
Complementary Knives
These blades are versatile, but they aren't made to be multi-use blades. If you want to twist, wrench, or fasten something with the knife, this type of knife may be predisposed to break. A multi-tool would be a superior pick for those types of tasks, and it makes a perfect complement to a survival knife.
For tasks that need a bigger knife, a machete or ax is likely a more appropriate option.
Brands
Almost all major knife makers manufacturer a knife in this category. Excellent options include blades from Fallkniven, Bark River Knife and Tool, and Ontario Knife Company.
More Info
To read about an introduction to survival tasks, go to the Wikipedia. It's succinct, but a fine jumping-off point. Wikipedia also has a good page on survival knives.