Electronically scan a book to import its content into a word-processing program. Save a snippet handwritten on a personal digital assistant (PDA) screen into a spreadsheet. Decipher a scrawled form or the zip code on an envelope. In all these cases, software translates typed or handwritten characters into digital text that can be edited, e-mailed, stored or used to tell a high-speed machine which direction to route a letter.

That software was originally known as optical character recognition; today the term refers just to recognizing text from a typeset page. Analyzing printed or cursive handwriting is called intelligent character recognition. Regardless of labels, the programs rely on similar algorithms to assess the features of an inkblot. The programs then compare the blot's features against mathematical models to determine which letter or number it most closely resembles.