  Given an ample, Hausdorff groupoid $\mathcal{G}$, and a unital commutative
ring $R$, we consider the Steinberg algebra $A_R(\mathcal {G})$. First we prove
a uniqueness theorem for this algebra and then, when $\mathcal{G}$ is graded by
a cocycle, we study graded ideals in $A_R(\mathcal {G})$. Applications are
given for two classes of ample groupoids, namely those coming from actions of
groups on graphs, and also to groupoids defined in terms of Boolean dynamical
systems.
