  We investigate the obstacle problem for a class of nonlinear equations driven
by nonlocal, possibly degenerate, integro-differential operators, whose model
is the fractional $p$-Laplacian operator with measurable coefficients. Amongst
other results, we will prove both the existence and uniqueness of the solutions
to the obstacle problem, and that these solutions inherit regularity
properties, such as boundedness, continuity and H\"older continuity (up to the
boundary), from the obstacle.
