In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil. The top of the bedrock is known as rockhead and identifying this, via excavations, drilling or geophysical methods, is an important task in most civil engineering projects. Superficial deposits (also known as drift) can be extremely thick, such that the bedrock lies hundreds of metres below the surface.

Bedrock may also experience subsurface weathering at its upper boundary, forming saprolite.

A solid geologic map of an area will usually show the distribution of differing rock types; i.e., rock that would be exposed at the surface if all soil or other superficial deposits were removed.

A remix is an alternative version of a recorded song, made from an original version. Sometimes this term is also used for alterations of media or recreation other than song (film, literature, beverages etc.).

A remixer uses audio mixing to compose an alternate master recording of a song, adding or subtracting elements, or simply changing the equalization, dynamics, pitch, tempo, playing time, or almost any other aspect of the various musical components. Some remixes involve substantial changes to the arrangement of a recorded work, but many are harmonic, such as creating a "vocal up" version of a song that emphasizes the lead singer's voice. Contemporary remixes are often produced in a Digital Audio Workstation (DAW), which allow producers to reorganize tracks and apply various effects.

Songs are remixed for a variety of reasons:

Remixes should not be confused with edits, which usually involve shortening a final stereo master for marketing or broadcasting purposes. Another distinction should be made between a remix and a cover. A remix song recombines audio pieces from a recording to create an altered version of the song. A cover is a recording of a song that was previously recorded by someone else.

A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth. Other stars are visible from Earth during the night, when they are not obscured by atmospheric phenomena, appearing as a multitude of fixed luminous points because of their immense distance. Historically, the most prominent stars on the celestial sphere were grouped together into constellations and asterisms, and the brightest stars gained proper names. Extensive catalogues of stars have been assembled by astronomers, which provide standardized star designations.

For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen in its core releasing energy that traverses the star's interior and then radiates into outer space. Almost all naturally occurring elements heavier than helium were created by stars, either via stellar nucleosynthesis during their lifetimes or by supernova nucleosynthesis when stars explode. Astronomers can determine the mass, age, chemical composition and many other properties of a star by observing its spectrum, luminosity and motion through space. The total mass of a star is the principal determinant in its evolution and eventual fate. Other characteristics of a star are determined by its evolutionary history, including diameter, rotation, movement and temperature. A plot of the temperature of many stars against their luminosities, known as a Hertzsprung–Russell diagram (H–R diagram), allows the age and evolutionary state of a star to be determined.