The terms paper knife and letter opener are often used interchangeably to refer to a knife-like desktop tool. In truth, they are actually for different functions and were in use at different times. Paper knives are used for cutting open the pages of hand-produced books where the folding of printed sheets creates some closed edges that require severing of the paper. Letter openers "evolved" from paper knives into longer, blunter blades for the sole purpose of opening envelopes. Letter openers may be designed from wood, metals such as stainless steel or pewter, plastic, sometimes even ivory, or a combination of materials.
Often the style of the handle is embellished or styled more so than the blade.