Primordial black holes and their gravitational-wave signatures - Bagui, Eleni; Clesse, Sebastien; De Luca, Valerio; Ezquiaga, Jose Maria; Franciolini, Gabriele; Garcia-Bellido, Juan; Joana, Cristian; Jain, Rajeev Kumar; Kuroyanagi, Sachiko; Musco, Ilia; Papanikolaou, Theodoros; Raccanelli, Alvise; et al. (Living Reviews In Relativity, 2025)