Epoch is a particle-in-cell (PIC) code widely used within plasma physics, particularly in the regime of laser-plasma interactions. PIC codes aim to self-consistently solve Maxwell’s equations in the presence of a large number of charged particles, many of which travel at relativistic velocities. Epoch and similar codes are often used to provide insight into the physics of matter interacting with extremely intense radiation, such as the conditions observed in inertial-confinement fusion (ICF) experiments or many astrophysical phenomena.