The term continuum in spectrography is commonly used for portions of a continuous spectrum not affected by a spectral feature such as a spectral line. To characterize a spectral line quantitatively, the received energy within the wavelength-range surrounding the line is measured, and compared with that of the continuum, by sampling nearby wavelength-ranges unaffected by any lines. The goal is to approximate the difference in received energy due specifically to the spectral line of interest. A typical star's spectral energy distribution (SED) shows an overall shape, largely that of a black-body spectrum, but with higher and lower spectral lines and bands. The overall shape is referred to as the continuum. The term can also be used on a smaller scale, e.g., around a spectral line in a portion of the spectrum that does not correspond to the black body spectrum.