The necessity of a knife is obvious to those who carry one, but not so to those who don’t. 

Yet, like fire, a knife has a myriad of uses ranging from a bushcraft knife to a combat knife and a general utility tool.  With a knife, you can cut, chop, batten, hammer, pry, create fire, make fuel for a fire, hunt, signal and protect yourself.

Yet, there are as many types of knife as there are situations in which you might find yourself requiring one.  A switch blade might be suitable for intimidatory purposes or slicing salami.  A butterfly knife is easily concealable but, with practice, can become an offensive weapon.  But whatever the application for your knife, you need to invest in a tool that is both practicable and efficient.  Rarely can one knife satisfy all the needs of your environment, so by understanding what constitutes a good knife, you will be able to make an informed decision.

The tang of the knife is the portion of the blade that extends into the handle.  The tang and the blade comprise one solid piece of steel and a full tang gives the knife its strength.  Sometimes, on cheaper knives, the blade is only connected to the top of the handle and will break off when under pressure.

The handle itself can be made from various products including natural woods, horns, polymers, hard rubber and plastic.  You need to consider whether you can hold the handle when you hand is wet or whether you are wearing gloves.  The handle should be strong enough so that the end can be used as a hammer and the guard will prevent your hand from slipping onto the blade inadvertently.  Some handles are hollow which tends to compromise the strength of the knife, but can provide a compartment for some survival items.  In other knives, survival kit can be placed in the side of the handles but you need to unscrew the handles to access the survival materials.  For this, you need a coin, washer or a screw driver which could get lost.

Despite the increased manufacture of ceramic blades which are both light weight and extremely sharp, their use is not recommended outside of a kitchen.  Some combat knives are made out of titanium and other non-magnetic material (to prevent mine detonation), but the majority of the knives are manufactured out of stainless steel or carbon steel.  Whilst stainless steel is very strong and does not rust quickly, a carbon steel will maintain its edge for longer and can be sharpened using natural materials including stones and a leather belt.

Unlike switch blades or butterfly knives that use thinner steel, it is recommended that your survival knife or combat knife should be about 0.5 centimetres thick which will enable you to chop and pry without damaging the blade.  Likewise, the size of your survival knife should be smaller than a combat knife owing to the type of uses that you can anticipate.  A combat knife is rarely used for combat purposes (for which a bayonet is preferred), but does need to withstand the rigorous of outdoor living.  Likewise, a bushcraft knife needs to be strong enough for you to operate outside in a hostile environment, but to complete chores that require some fine motor skills.

If survive in a wilderness, a small axe or a saw might be better suited for your survival.  In an urban environment, a small knife and a pry bar will be of greater use and enable you to fashion items to assist you in your hostile environment.

Owing to the sharpness of the blade, it is suggested that you use a lanyard on your survival knife by attaching the handle to your wrist via a cord.  In this way, you will not loose the knife and will always be able to maintain control of the blade. 

You still need a sheath to enable you to carry and draw your knife.  A cross-over strap where the handle meets the sheath is very effective, as a strap at the base or on the handle could allow the knife to slide out.

The sheath should also have a belt loop and a whole or attachment piece at the tip end of the sheath to strap the knife on your leg when on a belt.

Before considering these elements of a knife, you must first consider why you need a knife.  When travelling to hostile environments.  A knife is possibly the one tool you need, as it can provide you with many of the uses of a multi-tool device, yet with greater durability.