A bolster is the metal piece at the front of the handle, where the handle meets the blade. On traditional pocket knives it is a separate metal piece, often nickel silver; on kitchen knives it is a thick section of the blade steel itself.
On a traditional folder the bolster caps and protects the end of the handle material, hides the pins and springs, and adds weight at the front for balance. It is also the classic place for engraving.
On a fixed kitchen knife, the bolster is a thickened section between blade and handle that adds heft, protects your fingers from sliding forward, and gives a comfortable pinch grip.
On a well-made traditional knife the bolster should be flush with the handle material with no lip you can catch a fingernail on. A proud or gappy bolster is the clearest sign of rushed assembly.
Nickel silver, despite the name, contains no silver. It is a copper, nickel and zinc alloy named for its silver luster.
The term is not academic here. 163 of the products currently on our shelves describe this feature in their own manufacturer specifications, across 8 of the nine brands we stock. Examples in stock right now include Boker Trppr Micarta, Böker Lockback Thuya Wood, Case Peanut Abalone.
Everything below is pulled live from the catalog, so what you see is what is actually in the Woodlawn warehouse today.