Although the first knives were simply sharp pieces of flint, modern knives are generally more complex, and have a number of different parts and blade actions.

Parts of the modern knife

Modern knives generally have the following parts (there are more parts, but these are the main ones):

Blade: The flat part of the knife, the part used piercing or cutting. The blade may be made out of a number of steels, ceramic, plastic, or many other materials.

  • Point: The end of the blade, typically used for piercing.
  • Edge: The side(s) of the blade actually used for cutting, from the point to the heel. Most knives today are either plain edge (the edge is smooth), serrated edge (the edge has teeth or ridges), or partially-plain, partially-serrated edge (usually called just partially-serrated, or sometimes combo edge). Generally, knives only have one edged sharpened, although some combat knives have both edges sharpened. Some knives used only for stabbing (shivs, for example) forgo the edge.
  • Grind: The shape of the cross-section of the blade.
  • Spine: The top portion of the blade, opposite the edge, usually blunt and much thicker than the edge. Completely double-edged blades don't have spines, and blades with a partially-sharpened back edge have a smaller spine.
  • Fuller: The grooves on both sides of the flat of the blade. Thanks to wishful thinking, a popular myth has arisen that the fuller is a "blood groove", created for blood to run off the blade and make a thrust more damaging, although this is completely untrue. The fuller is actually cut out of the blade in order to lighten the knife.
  • Bolster: The thick, unsharpened part of the blade joining the handle. The bolster provides safety from the blade and adds balance to the knife.
  • Choil: Where the blade is unsharpened and possibly indented as it meets the handle. The choil may be used to prevent scratches to the handle when sharpening or as a forward-finger grip for choking up on the blade and increasing control during a cut. Not all blades have a choil.
  • Guard: A barrier between the blade and handle protecting the hand from slipping onto the blade or from being cut by the blade of another opponent. The guard is sometimes a part of the blade, sometimes a part of the handle, and sometimes separate from both. The guard is not present on all knives (especially folding knives).

Handle: The part of the knife that is gripped when in use. The handle may be made of metal, plastic, wood, bone, or a number of other materials. On some knives, the blade and handle are made from the same piece.

  • Tang: The part of the blade extending into the handle. Only fixed-blade knives have full tangs. The length of the tang affects the balance of the knife. Some tangs will extend through the handle, while others will not.
  • Butt (pommel): The end of the handle. Some butts have metal caps, and some may have lanyard holes.

Types of knives

Knives can be generally categorized into four groups based on the blade fixation in relation to the handle:

  • fixed blade knives: The blade's tang extends into the handle, so that the handle and blade are fixed together. The Bowie knife and the Kabar are both examples. Fixed blade knives are the strongest and most durable when compared to folding and sliding knives of equal quality, and also are the fastest and easiest to draw. However, fixed knives are also more difficult to carry, since they are twice the size of folding and sliding blade knives, and most cannot be slipped into pockets for safety reasons (if the knife slips out of the sheath). Fixed knives tend to be illegal in urban and suburban areas, but legal in the countryside.
  • folding blade knives: The blade folds into the handle when the knife is closed and folds out when the knife is open. The stereotypical folding blade knife is the Swiss Army Knife, although many folding knives have a single blade and different significantly from the typical Swiss Army Knife. Folding knives are generally the easiest to carry, as they can be slipped into pockets or clipped onto waistbands, with sliding blade knives a close second. Folding knives are usually legal to carry as long as the blade is reasonably small.
  • sliding blade knives: The blade comes out the top of the handle, either by gravity, as with a gravity knife, or by a spring mechanism, as in a switchblade. The out-the-front switchblade is the typical example of a sliding blade knife. Sliding blade knives are almost as easy to carry as folding knives, with the increased danger of having the knife open in your pocket and poke you. Sliding blade knives are usually easier and slightly faster to open than folding knives, but also less structurally sound by nature of the blade movement. Sliding blade knives are also more likely to break, because of the spring used to get the knife open. Sliding blade knives are often illegal, due to negative portrayal in the media.
  • ballistic knives: This kind of knife shoots its blade as a projectile. Yes, I realize the entire concept is ridiculous. Ballistic knives tend to be cheap quality and very illegal.

smartalix says The very first ballistic knife was originally a Spetznaz weapon, and thus very good. It was even used in the movice COmmando. I can easily believe follow-ons were cheap copies. The wu above yours contains an error you can correct in yours: the bowie knife is an American invention.

smartalix is definitely right about the Bowie knife being an American invention, as it was designed by Colonel James Bowie and created by James Black, and appears numerous times in the pages of American history. As for the original ballistic knife, I have never personally handled this knife, but I have read and been told that it was rather gimmicky and was rarely, if ever, used. The reader may decide for him/herself.