  We present a comprehensive formalism for the description of primordial black
hole formation in spherical symmetry based on the formalisms of Misner, Sharp,
and Hernandez, which can be used to predict whether or not a black hole will
form, and extract the resulting black hole mass when formation does occur.
Rigorous derivations of all aspects of the formalism are provided, including a
thorough investigation of appropriate initial and boundary conditions. We
connect our formalism with numerous other approaches in the literature. Some
implementation details for numerical code are provided. We include animations
of simulated primordial black hole formation as supplemental material.
