envelope with one or more openings through which part of the contents can be seen. Windows may be completely open or may have a transparent plastic or paper covering. Most window envelopes, especially those used to mail invoices, are used to display the name and address of the recipient on a form inside the envelope, thus saving the expense of addressing an envelope. However, many window envelopes used for direct-mail promotions display other portions of the package components, adding (or changing) color, copy, and graphics on the outer envelope or personalizing the outer envelope for each recipient, without the expense of printing special envelopes. For example, some of the copy elements shown through windows are "reply by" dates; tokens with copy imprinted on them, such as "FREE"; curiosity-arousing portions of the copy or graphics inside, such as the question portion of a multiple-choice quiz; or portions of what resembles a bank check.
The cost of a window envelope depends upon the size of the envelope, the type (standard or nonstandard), and the number of windows. In most cases, a window envelope will cost slightly more than a similar-size fullface envelope.
