  Braidoids generalize the classical braids and form a counterpart theory to
the theory of planar knotoids, just as the theory of braids does for the theory
of knots. In this paper, we introduce basic notions of braidoids, a closure
operation for braidoids, we prove an analogue of the Alexander theorem, that
is, an algorithm that turns a knotoid into a braidoid, and we formulate and
prove a geometric analogue of the Markov theorem for braidoids using the
$L$-moves.
