▪ Abstract  We review the current status of determinations of the b-quark mass, mb. We describe the theoretical tools required for determining mb, with particular emphasis on effective field theories both in the continuum and on the lattice. We present several definitions of mb and highlight their advantages and disadvantages. Finally, we discuss the determinations of mb from [Formula: see text] systems, b-flavored hadrons, and high-energy processes, with careful attention to the corresponding theoretical uncertainties.