Fundamental

[Sarah]

Pertaining to the foundation or basis; serving for thefoundation. Hence: Essential, as an element, principle, or law;important; original; elementary; as, a fundamental truth; afundamental axiom.The fundamental reasons of this war. Shak.Some fundamental antithesis in nature. Whewell.Fundamental bass (Mus.), the root note of a chord; a bass formed ofthe roots or fundamental tones of the chords.-- Fundamental chord (Mus.), a chord, the lowest tone of which isits root.-- Fundamental colors, red, green, and violet-blue. See Primarycolors, under Color.

[Sarah]

The very basic or more simplistic form /version that can make up something of a larger and more complex structure/format/design/ect.

[Justin Bieber]

Forming a necessary base or core; of central importance.