  Blazars, a subset of powerful active galactic nuclei, feature relativistic
jets that shine in a broadband electromagnetic radiation, e. g. from radio to
TeV emission. Here I present the results of the studies that explore gamma-ray
and optical variability properties of a sample of gamma-ray bright sources
Several methods of time-series analyses are performed on the decade-long
optical and Fermi/LAT observations. The main results are as follows: The
sources are found highly variable in both the bands, and the gamma-ray power
spectral density is found to be consistent with flicker noise suggesting
long-memory processes at work. While comparing two emission, not only the
overall optical and the $\gamma$-ray emission are highly correlated but also
both the observation distributions exhibit heavy tailed log-normal distribution
and linear RMS-flux relation. In addition, in some of the sources indications
of quasi-periodic oscillation were revealed with similar characteristic
timescales in both the bands. We discuss the results in light of current blazar
models with relativistic shocks propagating down the jet viewed close to the
line of sight.
