Compact Disc in the context of Mini CD

Advertising mail, also known as direct mail (by its senders), junk mail (by its recipients), mailshot or admail (North America), letterbox drop or letterboxing (Australia), is the delivery of advertising material to recipients of postal mail. The delivery of advertising mail forms a large and growing service for many postal services, and direct-mail marketing forms a significant portion of the direct marketing industry. Some organizations attempt to help people opt out of receiving advertising mail, in many cases motivated by a concern over its negative environmental impact.

Advertising mail includes advertising circulars, plastic mailers, coupon envelopes (Money Mailer, Valpak), catalogs, CDs, "pre-approved" credit card applications, and other commercial merchandising materials delivered to homes and businesses. It may be addressed to pre-selected individuals, or unaddressed and delivered on a neighbourhood-by-neighbourhood basis.

An entertainment center (or centre), also known as an entertainment complex or a home entertainment center, is a piece of furniture designed to house consumer electronic appliances and components. It is sometimes a large cabinet with an exterior styled to appear like upscale furniture and an interior dedicated to electronic gear, such as home audio, television sets and video game equipment.

Antique or modern reproduction armoires or standing cabinets are used for entertainment centers, as are shelves and shelving systems. Part of the purpose of an entertainment center is to neatly house the many wires and cables that are associated with audio and video components, and they often contain dedicated areas (either drawers or other spaces) for storage of records, videotapes, CDs and/or DVDs.

Video game packaging refers to the physical storage of the contents of a PC or console game, both for safekeeping and shop display. In the past, a number of materials and packaging designs were used, mostly paperboard or plastic. Today, most physical game releases are shipped in (CD) jewel cases or (DVD) keep cases, with little differences between them.

Aside from the actual game, many items may be included inside, such as an instruction booklet, teasers of upcoming games, subscription offers to magazines, other advertisements, or any hardware that may be needed for any extra features of the game.

Gapless playback is the uninterrupted playback of consecutive audio tracks, such that relative time distances in the original audio source are preserved over track boundaries on playback. For this to be useful, other artifacts (than timing-related ones) at track boundaries should not be severed either. Gapless playback is common with compact discs, gramophone records, or tapes, but is not always available with other formats that employ compressed digital audio. The absence of gapless playback is a source of annoyance to listeners of music where tracks are meant to segue into each other, such as some classical music (opera in particular), progressive rock, concept albums, electronic music, and live recordings with audience noise between tracks.

In sound recording, dubbing is the transfer or copying of previously recorded audio material from one medium to another of the same or a different type. It may be done with a machine designed for this purpose, or by connecting two different machines: one to play back and one to record the signal. The purpose of dubbing may be simply to make multiple copies of audio programs, or it may be done to preserve programs on old media which are deteriorating and may otherwise be lost.

One type of dubbing device combines two different storage media, such as an audio cassette deck that incorporates a Compact Disc recorder. Such a device enables the transfer of audio programs from an obsolete medium to a widely used medium. It may also simply be used to transfer material between two types of media which are popular in different settings, so that material originating in one type of environment can be used in another. An example of the latter would be the dubbing of a Digital BetaCam videocassette to DVD.