  Core-collapse supernovae are among the most powerful explosions in the
universe, emitting thermal neutrinos that carry away the majority of the
gravitational binding energy released. These neutrinos create a diffuse
supernova neutrino background (DSNB), one of the largest energy budgets among
all radiation backgrounds. Detecting the DSNB is a crucial goal of modern
high-energy astrophysics and particle physics, providing valuable insights in
both core-collapse modeling, neutrino physics, and cosmic supernova rate
history. In this review, we discuss the key ingredients of DSNB calculation and
what we can learn from future detections, including black-hole formation and
non-standard neutrino interactions. Additionally, we provide an overview of the
latest updates in neutrino experiments, which could lead to the detection of
the DSNB in the next decade. With the promise of this breakthrough discovery on
the horizon, the study of DSNB holds enormous potential for advancing our
understanding of the Universe.
