The first stamps were produced by private companies under contract to the government. In Great Britain private concerns still print the stamps. In the United States, except for a brief period, stamps have been produced by the Bureau of Engraving and Printing which also makes the paper currency, revenue stamps, and bonds for the government.

Most modern stamps carry an illustration, often a portrait, on the face (or obverse). This illustration and the postage value make up the actual stamp, not the paper. Postage machines, which imprint the correct postage on each piece of mail, have replaced the use of regular stamps in many businesses.

For regular post office stamps a designer first draws the picture and the frame, complete to the smallest detail. One of several processes is used to get the design ready for printing. The oldest process, still widely used, is engraving. Other common methods are lithography and typography. The first British stamps were made by intaglio printing. Other early stamps were printed directly from handset type when other methods were unavailable.

An engraved stamp has lines raised a little above the surface. In typography the lines are slightly pressed into the paper. Sometimes the lines show through on the back of the stamp. Engraving gives the sharpest and finest lines. Typography looks flat by comparison. In lithography, lines are fuzzier and the whole surface appears duller.

Printing is done on a flat-bed press or a rotary press. Since the early 1920s most stamps in the United States have been printed on fast rotary presses. On such a press the plate is stretched slightly when it is curved to fit the press cylinder. This results in stamps that are either a little longer or a little wider than the stamps printed on a flatbed press.

The paper used in stamps is either wove or laid. Laid paper has ribbed lines, while wove paper does not. The United States uses only wove paper for its adhesive stamps, but its embossed stamped envelopes use laid paper.

Either type of paper may have watermarks worked into it when it is made. To see a watermark, the paper must be held up to light. Watermarks on stamp paper are normally special designs used exclusively by the government issuing the stamp. A watermark may appear on each stamp, or it may be spread across the whole sheet with only part of the mark appearing on each stamp. Many nations still use watermarked paper, and watermarks are more readily visible on the currency than on stamps. The United States stopped using watermarked paper in 1915.

After being gummed, the sheets may have small holes called perforations punched between the stamps. When the first stamps were made there was no provision for separating one from another. To do so required a knife or a pair of scissors. In 1847 an Irish engineer named Henry Archer submitted a plan to the British Post Office for perforating stamp sheets. By 1854 Archer's machine was sufficiently perfected to produce the first perforated stamps. The United States began using a perforating machine in 1857.

There is another separation process called rouletting, from the French roulette, for “little wheel.” In rouletting, small wheels slit the paper instead of punching tiny holes in it.

Errors or differences in stamp manufacturing inadvertently create valuable items for collectors. From 1854 to 1924 some British stamps of the same value were issued on paper with different watermarks. Collectors can differentiate stamps by perforations. To some collectors a difference in the number of perforations creates a separate, collectible variety.

It is the more spectacular errors in printing that have created some truly valuable stamps. One of the most famous errors occurred at the Bureau of Engraving and Printing in 1916. A plate with 400 red two-cent stamps bearing a George Washington portrait had three engravings badly worn. These were accidentally replaced with three five-cent engravings bearing the identical portrait. As a result, each new sheet of what should have been 400, red, two-cent stamps mistakenly had three, red, five-cent stamps. When the error was discovered, the plate was corrected, but by that time some of the faulty sheets had been sold, putting a few rare and highly collectible stamps on the market. In 1918 the Bureau printed some sheets of airmail stamps with an upside-down airplane. Only one sheet reached the public, making it one of the truly rare collectors' items.