Superluminous supernovae (SLSNe) are a rare class of transients discovered by untargeted surveys in the past decade, characterized by bolometric luminosities 10-100 times those of normal core-collapse and Type Ia SN. Now more than a decade after their discovery, the energy sources and progenitor stars of the H-poor SLSNe are still debated. In this talk, I will provide a review of H-poor SLSNe, addressing their nature from two angles: 1) characterizing the explosions themselves and comparing the observed properties to model predictions, and 2) constraining the progenitor population through studies of SLSN host galaxy environments.