Strong gravitational lensing and microlensing of supernovae (SNe) are emerging as a new probe of cosmology and astrophysics. This review provides an overview starting with the first discoveries of strongly lensed SNe. It describes how time delays between multiple SN images can measure cosmological distances and constrain the Hubble constant, which remains debated.

New methods for measuring these time delays have been developed, and the sample from the upcoming Rubin Observatory Legacy Survey of Space and Time (LSST) is expected to provide competitive cosmological constraints. Lensed SNe are also powerful astrophysical probes used to constrain SN progenitors, acquire high-z spectra through magnification, infer SN sizes, and measure galactic dust properties. The main challenge is the rarity and difficulty of finding lensed SNe.

The authors describe methods to find them, forecast properties of the expected LSST sample, and summarize observational follow-up needs. They anticipate an exciting period ahead with a boom in lensed SN discoveries. The review targets Suyu et al. (2024).