  In this short review I present the status of the global 21-cm signal detected
by EDGES in March 2018. It is organized in three parts. First, I present the
EDGES experiment and the fitting procedure used by the collaboration to extract
the tiny 21-cm signal from large foregrounds of galactic synchrotron emission.
Then, I review the physics behind the global 21-cm signature and I explain why
the measured absorption feature is anomalous with respect to the predictions
from standard astrophysics. I conclude with the implications for Beyond
Standard Model (BSM) physics coming from the EDGES discovery.
