Ado's theorem states that every finite-dimensional Lie algebra of characteristic 
has a faithful finite-dimensional
representation.
Ado's Theorem
See also
Iwasawa's Theorem, Lie AlgebraExplore with Wolfram|Alpha
References
Jacobson, N. Lie Algebras. New York: Dover, pp. 202-203, 1979.Referenced on Wolfram|Alpha
Ado's TheoremCite this as:
Weisstein, Eric W. "Ado's Theorem." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/AdosTheorem.html