One of the world's most popular hobbies, philately is the study and collection of stamps and postal items. Many hobbyists collect regular postage stamps; others collect special use issues, some of which are unrelated to postal service. National postal administrations or smaller political entities and their lawful competitors issue stamps. So too do local posts, express companies, and even forgers. While collectors organize their collections around personal interests, they frequently enjoy the philatelic pursuits of other collectors. Consequently, philately has fostered local clubs, national societies, major annual exhibitions, and innumerable publications since its origins in nineteenth-century England. England introduced the world's first postage stamp, the Penny Black, in 1840. Across the English Channel in France, a different philosophy about collecting emerged. The 'French School' proposed classifying stamps, arguing that "the history of every design is worth tracing through the various mutations of shade, paper, watermark and perforation." Devotees of this viewpoint cultivated the scholarly aspects of the hobby, leading some people to call philately a science. Further, the French invented one of the hobby's primary tools, the perforation gauge. As more countries issued stamps and mail burgeoned within and among nations, a new field of interest emerged - postal history. Its focus is not only the history of postal systems but also the history of related uses of stamps on mail. The history of postal systems is called 'Postal Operations' rather than 'Postal History'. Philately, then, encompasses not only stamps per se but also a broad-based interpretation of the physical mail, especially the outer covers of the communication that received the postage, the postmark and backstamp, carriers' marks, and special services afforded the piece.Mary H. Lawson, US National Postal Museum