Survival knives are knives which have been designed to be used in a wilderness or survival situation. They come in a variety of designs and they are one of the most valuable additions to your pack. However, because you will find many varieties of knives being sold described as survival knives it is important that you pick a good quality, robust knife with the correct construction and features.
One of the extremely important features of good quality survival knives will be one that will not be apparent to the eye but is vital to the strength of the knife and that is that it is constructed with what is known as a full tang. The tang of the knife is the extension of the blade which is covered by the handle. In some cheaper knives, the blade can be screwed and glued to the handle, whereas with a full tang the handle is fully part of the blade, which of course eliminates this weak spot. If a knife cannot be relied upon to cope with hard regular use then it cannot really be called a survival knife.
There are two materials which are used in the construction of survival knives, stainless steel, and carbon steel. Stainless steel blades are the most common and have the advantage of being non-rusting, an important quality if you are in a damp environment. Carbon steel blades are not rust proof and will need to be regularly oiled to keep them in good condition, however, many users consider that they can be sharpened to a keener edge and will hold that edge longer than a stainless steel blade; it's really a matter of personal choice.
They also come in a choice of serrated and smooth edged blades. Serrated blades are better at cutting through materials and light sawing whereas a smooth edged blade is better at carving, skinning and food preparation. I personally find a smooth edged blade to be more versatile and the clincher for me is that they are far easier to keep sharp, a serrated blade needing a specialized tool which could be easily lost in a survival situation. Some of them have a saw-toothed top edge to the blade for wood cutting although I find their short length tends to limit their effectiveness. Also, it makes it difficult to apply pressure to the back of the knife, for example when splitting wood.
Good, well made, versatile, they are one of the most important additions you can make to your survival equipment so a little time spent understanding their construction and uses will enable you to purchase a knife which will be perfect for your needs and which will reward you with years of good service.