Advertising is a marketing communication that employs an openly sponsored, non-personal message to promote or sell a product, service or idea. Sponsors of advertising are typically businesses wishing to promote their products or services. Advertising is differentiated from public relations in that an advertiser pays for and has control over the message.[from wikipedia]

A door is a panel that makes an opening in a building, room or vehicle. Doors are usually made of a hard, impermeable, and hard-to-break substance (such as wood or metal), but sometimes consisting of a hard frame into which windows or screens have been fitted. Doors are often attached by hinges to a frame. Doors make ingress into or egress from a building, room, or vehicle easier to manage.[from wikipedia]

Effective application of countermeasures can be complicated by several factors, including media that are inaccessible, media that cannot effectively be erased, advanced storage systems that maintain histories of data throughout the data's life cycle, and persistence of data in memory that is typically considered volatile.[from wikipedia]

A window is an opening in a wall, door, roof, or vehicle that allows the passage of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent material, a sash set in a frame in the opening; the sash and frame are also referred to as a window.[from wikipedia]

Murals painted on an object that is best, but not exclusivly, viewed from a passenger car of a railroad line.

A street mural is any piece of artwork painted or applied directly on an exterior wall, ceiling or other large permanent surface. [paraphrased from wikipedia]