Envelope in the context of Discharge tube

Sealing wax is a wax material of a seal which, after melting, hardens quickly (to paper, parchment, ribbons and wire, and other material), forming a bond that is difficult to break without noticeable tampering. Wax is used to verify that something such as a document is unopened, to verify the sender's identity (for example with a seal stamp or signet ring), and as decoration. Sealing wax can also be used to take impressions of other seals. Wax was used to seal letters close and later, from about the 16th century, envelopes. Long before sealing wax was employed, the Romans used bitumen for this purpose.

A postcard or post card is a piece of thick paper or thin cardboard, typically rectangular, intended for writing and mailing without an envelope. Non-rectangular shapes may also be used but are rare.

In some places, one can send a postcard for a lower fee than a letter. Stamp collectors distinguish between postcards (which require a postage stamp) and postal cards (which have the postage pre-printed on them). While a postcard is usually printed and sold by a private company, individual or organization, a postal card is issued by the relevant postal authority (often with pre-printed postage).

A postage stamp is a small piece of paper issued by a post office, postal administration, or other authorized vendors to customers who pay postage (the cost involved in moving, insuring, or registering mail). Then the stamp is affixed to the face or address-side of any item of mail—an envelope or other postal cover (e.g., packet, box, mailing cylinder)—which they wish to send. The item is then processed by the postal system, where a postmark or cancellation mark—in modern usage indicating date and point of origin of mailing—is applied to the stamp and its left and right sides to prevent its reuse. Next the item is delivered to its address.

Always featuring the name of the issuing nation (with the exception of the United Kingdom), a denomination of its value, and often an illustration of persons, events, institutions, or natural realities that symbolize the nation's traditions and values, every stamp is printed on a piece of usually rectangular, but sometimes triangular or otherwise shaped special custom-made paper whose back is either glazed with an adhesive gum or self-adhesive.

A greeting card is a piece of card stock, usually with an illustration or photo on its front cover, made of high-quality paper featuring an expression of friendship, love, celebration, or other sentiment. Greeting cards are traditionally given on special occasions such as birthdays, weddings, anniversaries, baby showers, baptisms, and graduations, or during the holidays, including New Year's Day, Valentine's Day, Easter, Halloween, Thanksgiving, and Christmas. Greeting cards can also be sent to express other feelings, such as giving thanks, sympathy, encouragement, or best wishes to get well from an illness or injury.

Greeting cards are usually packaged using an envelope and come in a variety of styles. There are both mass-produced and handmade versions available and they may be distributed by hundreds of companies large and small. While typically inexpensive, more elaborate cards with die-cuts, pop-ups, sound elements or glued-on decorations may be more expensive.

A pocket is a small bag- or envelope-shaped compartment that is either sewn into or attached to clothing, designed for carrying small items. Pockets are also found on luggage, backpacks, and similar containers. Historically, the term could also refer to a separate pouch or small bag.

A gas-filled tube, also commonly known as a discharge tube or formerly as a Plücker tube, is an arrangement of electrodes in a gas within an insulating, temperature-resistant envelope. Gas-filled tubes exploit phenomena related to electric discharge in gases, and operate by ionizing the gas with an applied voltage sufficient to cause electrical conduction by the underlying phenomena of the Townsend discharge. A gas-discharge lamp is an electric light using a gas-filled tube; these include fluorescent lamps, metal-halide lamps, sodium-vapor lamps, and neon lights. Specialized gas-filled tubes such as krytrons, thyratrons, and ignitrons are used as switching devices in electric devices.

The voltage required to initiate and sustain discharge is dependent on the pressure and composition of the fill gas and geometry of the tube. Although the envelope is typically glass, power tubes often use ceramics, and military tubes often use glass-lined metal. Both hot cathode and cold cathode type devices are encountered.

Postal cards are postal stationery with an imprinted stamp or indicium signifying the prepayment of postage. They are sold by postal authorities. On January 26, 1869, Dr. Emanuel Herrmann of Austria described the advantages of a Correspondenz Karte. By October 1, 1869 the world's first postal card was produced by Austria-Hungary. They caught on quickly. By the end of 1870, Great Britain, Finland, Switzerland and Württemberg joined the countries issuing postal cards. In the United States, they were first produced in 1873. Some of the forms taken by postal cards include the regular single card which may be commemorative or definitive, attached message-reply cards, airmail postal cards, and official postal cards used for official government business with a "penalty for private use".

To the post office, there were positive advantages to postal cards as opposed to correspondence in envelopes. The cards were lighter and less bulky than letters and they were all the same size. The result was that they occupied less than one third of the space required by the same number of letters. To the public there were also advantages. They were simple and cheap making them an instant success. Britain had a half-penny rate to begin with. The U.S. "penny postcard" rate lasted through 1951.

A postmark is a postal marking made on an envelope, parcel, postcard or the like, indicating the place, date and time that the item was delivered into the care of a postal service, or sometimes indicating where and when received or in transit. Modern postmarks are often applied simultaneously with the cancellation or killer that marks postage stamps as having been used. Sometimes a postmark alone is used to cancel stamps, and the two terms are often used interchangeably. Postmarks may be applied by handstamp or machine, using methods such as rollers or inkjets, while digital postmarks are a recent innovation.

Die cutting is the general process of using a die to shear webs of low-strength materials, such as rubber, fibre, foil, cloth, paper, corrugated fibreboard, chipboard, paperboard, plastics, pressure-sensitive adhesive tapes, foam, and sheet metal. In the metalworking and leather industries, the process is known as clicking and the machine may be referred to as a clicking machine. When a dinking die or dinking machine is used, the process is known as dinking. Commonly produced items using this process include gaskets, labels, tokens, corrugated boxes, and envelopes.

Die cutting started as a process of cutting leather for the shoe industry in the mid-19th century. It is now sophisticated enough to cut through just one layer of a laminate, so it is now used on labels, postage stamps, and other stickers; this type of die cutting is known as kiss cutting.