Abstract: After a brief introduction to black hole evaporation, I will review that Hawking’s calculation of particle production is based on the semi-classical limit of a fixed metric. As the black hole evolves, however, backreaction can invalidate this approximation after a finite time. This raises two fundamental questions: how long does the semiclassical description remain valid, and what happens once it breaks down?
To address them, I will construct an effective description of information storage in black holes. This leads to the memory burden effect, which can arise well before half the black hole mass is lost and which drastically slows down evaporation. I will conclude by discussing observational signatures of memory burden in primordial black holes, particularly in gravitational waves and high-energy astroparticles.