Envelope

An envelope holds a letter or a card.

Most are made of thin paper. They have flaps that fold over the middle. People use glue to keep the flaps shut.

Some have a clear window on the front. This lets you see the address inside. Long ago, people used clay to make envelopes.

They even used wallpaper for envelopes during a war. Envelopes help us send mail to friends.

An envelope is a thin cover for flat things. Most hold letters or cards.

Most are made from paper. They are cut into shapes like a kite or a cross. This allows the sides to fold around a middle part. These sides are called flaps. People use glue or paste to keep the flaps shut.

Some envelopes have a window. This is a hole in the front. A clear film covers the hole. This lets you see the address on the letter inside.

Envelopes have a long history. The first ones were made in the ancient Middle East. They were hollow clay spheres used for money.

Later, people in China used paper envelopes for gifts. In the United States, people used wallpaper for envelopes during the Civil War. Today, most envelopes are made by machines. Over 400 billion are made every year.

An envelope is a common way to package flat objects. Most people use them to hold letters or cards.

These covers are usually made of thin, flat material like paper. To make an envelope, a sheet is cut into a specific shape. Common shapes include a rhombus, a kite, or a short-arm cross. These shapes allow the sides to fold around a central rectangular area. This creates a rectangular enclosure with four flaps on the back.

There are many ways to make these flaps stay shut. Most envelopes are pasted or gummed together at the overlaps. Some people might use a wax seal to hold the top flap.

Some envelopes have a special window cut into the front. This window lets you see the address on the letter inside. This saves people from having to write the address twice. Americus F. Callahan designed this windowed style in 1901. He received a patent for it in 1902.

Envelopes have been around for a very long time. The first known envelopes were made in the ancient Middle East. They were hollow clay spheres used to hold money tokens.

Researchers Jacques de Morgan and Roland de Mecquenem discovered these in 1901 and 1907. Later, paper envelopes were used in China to store money gifts. During the U.S. Civil War, some people used wallpaper to make envelopes. This happened because they faced financial hardships.

Making envelopes used to be a slow, handmade job. Before 1840, every single envelope was cut by hand from paper. George Wilson changed this in the United Kingdom in 1840. He patented a way to tile many patterns across one large sheet. This method helped reduce the amount of wasted paper.

In 1845, Edwin Hill and Warren de la Rue patented a machine. This steam-driven machine could cut, crease, and fold the shapes. Today, machines make most of the 400 billion envelopes used each year.

Envelopes come in many different sizes and styles around the world. In the United States, the No. 10 envelope is the standard for business.

Other countries use different systems, like the DIN standards in Germany. In Japan, some envelopes open on the short side. Others, called Western-style, open on the long side. You might even see special envelopes used for weddings or funerals. These can use different colored cords to show the occasion.

An envelope is a common packaging item used to contain flat objects. Most often, people use them to hold letters or cards. They are usually made from thin, flat materials like paper.

The structure of a traditional envelope relies on specific geometric shapes. These shapes include the rhombus, the kite, or the short-arm cross. These shapes allow the sides of the paper to fold around a central rectangular area. This process creates a rectangular-faced enclosure. On the reverse side, the folding creates an arrangement of four flaps.

There are several ways to secure these flaps to keep the contents safe. Most modern envelopes are pasted or gummed together at the overlaps. In some cases, a person might use a wax seal to secure the topmost flap at a single point. Some envelopes include a window, which is a hole cut into the front side. This window allows the paper inside to be seen. This design is useful because the receiving address printed on the letter becomes visible. This saves the sender from having to write the address twice.

Americus F. Callahan designed this windowed envelope in 1901 and patented it in 1902.

Envelopes have evolved through many different forms over thousands of years. The earliest known envelopes date back to 3500 to 3200 BC in the ancient Middle East. These were not made of paper, but were hollow clay spheres. They were molded around financial tokens for use in private transactions. Jacques de Morgan and Roland de Mecquenem discovered these in 1901 and 1907. Much later, paper envelopes were developed in China. Known as chih poh, these were used to store money gifts. During the Southern Song dynasty, the Chinese imperial court used them to distribute money to officials.

Before the industrial age, making envelopes was a slow, manual process. Up until 1840, every envelope was handmade. Workers had to individually cut each one from a rectangular sheet. George Wilson of the United Kingdom changed this in 1840. He patented a method called tessellating, which means tiling many patterns across a large sheet. This method reduced the amount of paper waste produced during cutting. In 1845, Edwin Hill and Warren de la Rue patented a steam-driven machine. This machine could cut, crease, and fold the shapes.

Today, the scale of envelope production is massive. Most of the 400 billion envelopes made worldwide every year are machine-made.

Envelopes also serve many specialized roles in modern society. A return envelope is a smaller, pre-addressed envelope included inside a larger one. These are used for courtesy replies or business mail. Some envelopes are even designed to be reused as the return envelope to save money. The direct mail industry uses these as a way to get responses from customers. Some people even use wallpaper to make envelopes when they face financial hardships, as seen during the U.S. Civil War.

Global standards help organize the many different sizes of envelopes. The International Organization for Standardization once used ISO 269 to define sizes like C4, C5, and C6. While these were withdrawn in 2009, other systems remain. Germany uses the DIN 678 standard. The DL size in Germany comes from the "DIN Lang" or "Long" size from the 1920s. In the United States, there are dozens of sizes. The No. 10 envelope is the standard size for business. The U.S. Postal Service has specific rules for letter pricing. For example, a letter must be at least 0.007 inches thick.

Different cultures also use envelopes for specific social traditions. In Japan, envelopes can be categorized by how they open. Traditional Kaku and Chou envelopes open on the short side. Western-style envelopes, called Yōgata, open on the long side. Envelopes are also used to express emotions in ceremonies. In Japan, white and black cords on an envelope represent death for funerals. Red and silver cords are used for weddings.

These cultural uses show how a simple piece of paper can hold deep social meaning.