  In this thesis, following F. Brown's point of view, we look at the Hopf
algebra structure of motivic cyclotomic multiple zeta values, which are motivic
periods of the fundamental groupoid of $\mathbb{P}^{1} \diagdown \lbrace 0,
\mu_{N}, \infty \rbrace $. By application of a surjective \textit{period} map
(which, under Grothendieck's period conjecture, is an isomorphism), we deduce
results (such as generating families, identities, etc.) on cyclotomic multiple
zeta values, which are complex numbers. The coaction of this Hopf algebra
(explicitly given by a combinatorial formula from A. Goncharov and F. Brown's
works) is the dual of the action of a so-called \textit{motivic} Galois group
on these specific motivic periods. This entire study was actually motivated by
the hope of a Galois theory for periods, which should extend the usual Galois
theory for algebraic numbers.
