An album is a packaged collection of related things. The most common types of albums are record albums and photo albums.
Photo albums collect a series of photographs in a book. Some albums have compartments which the photos may be slipped in to; older style albums often were simply books of heavy paper which photos could be glued to or attached to with adhesive corners.
The term record album originally referred to a collection of 78 RPM gramophone or phonograph records kept together in a book resembling a photo album. Later "album" came to refer to a single long playing 33 1/3 RPM 12" record of songs or music, as one disc contained as much music as an old-style album of records. Now that the vinyl record is less common, the term is applied to any hard-pressed full length sound recording (including CD, Minidisc, and cassette.)
Now that albums are on CD and new media, the matter of how long an album should be is open to debate. One author suggested at least eight tracks, but there are albums of fewer tracks. According to the rules of the British Charts, a recording counts as an album if either it has at least four tracks or lasts more than 20 minutes.
Returning to the older meaning of the term, there are now albums of compact discs; collections of cds in a single package.