Mailing envelopes are a type of packaging used for posting items, and are a basic stationary product in many business. An envelope is typically flat and acts as a container, complete with sealable flap. They are normally used to send flat items, such as documents, letters and cards. However, padded envelopes containing bubble wrap and often referred to as 'bubble bags' or 'jiffy bags' can be used to protect and send small parcels. Padded envelopes are employed when extra protection is required for more valuable or fragile contents.

Additional Features

• Some envelopes feature a window, where the address details from a letter are easily visible, saving duplication in re-writing or printing address information.

• Some varieties are self-adhesive. You simply stick the flap down to seal the letter, rather than moistening the sealant.

• Envelopes with additional strengthening, such as a hard back, offer a degree of protection against bending and are particularly useful for sending valuable documents (such as certificates) through the post.

• Envelopes can also help to keep information confidential by sealing them until they reach their intended recipient or reader.

Common envelope sizes

Although many types of envelope are available, there are a range of standard sizes that are most commonly used:

• DL: Measuring 110 x 220 mm, this size fits a piece of A4 paper that has been folded into three. Compliments slips are often printed just slightly smaller than the size of this envelope, so that they easily fit in.

• C4: Measuring 324 x 229 mm, this size and easily accommodates unfolded A4 paper.

• C5: Measuring 162 x 229 mm, this size accommodates unfolded A5 paper (or a piece of A4 folded in half.)

• C6: Measuring 114 x 162 mm, A6 paper fits in a C6 envelope (or A5 paper folded in half, or A4 paper folder into quarters.)