The Baldwin effect in astronomy describes a relationship between continuum and emission-line fluxes observed in the electromagnetic spectra of quasars and active galactic nuclei, namely an anticorrelation between the equivalent width, Wλ, of a spectral line and the continuum luminosity, L, in broad UV optical emission lines. This means that the ratio of brightness of the emission line to the brightness of the nearby continuum decreases with increasing luminosity of the continuum.