Characterization of Variability in Blazar Light curves

Blazars represent dominant population of the extragalactic $\gamma$-ray sources in the Universe. These sources exhibit some characteristic properties like strong and non-thermal continuum emission over the entire electromagnetic spectrum from radio to TeV $\gamma$-rays with rapid variability on all timescales. The emission at radio and optical wavelengths is highly polarized with significant variation. The fastest variability in the blazar emission is observed during the flaring activity which is an important observational property of blazars. In this paper, we describe various methods to characterize the temporal variability in the multi-wavelength light curves of blazars. We also provide a detailed description of the set of statistical parameters which are used to quantify the level of variability present in the time-series. Implications of the informations derived from the variability study to probe the physics of blazars using multi-wavelength observations are also discussed.