What are envelopes?

Some articles on envelopes, envelope:

Paper Knife
... A paper knife or letter opener is a knife-like object used to open envelopes or to slit uncut pages of books ... are also available, which work by using motors to slide the envelopes across a blade ... These have the advantage of being able to handle a greater volume of envelopes, but the blade can slice into the contents of the envelope and damage them ...
Postage Stamps And Postal History Of Malta - Postal Stationery
... to be issued by Malta were in 1885 when postcards, newspaper wrappers and registration envelopes were issued ... Post paid envelopes were first issued in 1900 and the only new type of postal stationery to be issued by Malta were aerogrammes which were first issued in 1969 ... Up to 2002 a total of 48 different registration envelopes have been identified as having been produced, although some varieties exist on some of them ...
Columbian Issue - Related Releases - Envelopes
... A series of four envelopes, or preprinted postal stationery, was issued along with the stamp set ...
Circumstellar Envelope
... Circumstellar envelope is the part of the star having roughly spherical shape and not gravitationally bound to the star core ... Usually circumstellar envelopes are formed from the dense stellar wind, or they are present before formation of the star ... Circumstellar envelopes of the old stars (Mira variables and OH/IR stars) are eventually evolving into Protoplanetary nebulae, and circumstellar envelopes of the young stellar objects ...
Types of Circumstellar Envelopes
... Circumstellar envelopes of AGB stars Circumstellar envelopes around young stellar objects ...