Blazars are a type of AGN that is characterized by a relativistic jet pointed towards the observer.

Blazars are believed to be powered by the accretion of matter onto a supermassive black hole.

The Véron-Cetty and Véron Catalog of Quasars and Active Galactic Nuclei is the most comprehensive catalog of blazars, containing over 100,000 objects.

Catalogs of blazars serve multiple purposes, including providing a comprehensive list of blazars for astronomers to study, helping astronomers identify new blazars, and tracking the evolution of blazars over time.

Compiling catalogs of blazars is challenging due to the faintness of blazars, the variability of blazars, and the difficulty in distinguishing blazars from other types of AGN.

Catalogs of blazars can be used to study the evolution of blazars by comparing the properties of blazars at different redshifts and by tracking the changes in the properties of blazars over time.

Catalogs of blazars typically include information on the position, redshift, flux density, polarization, and other properties of blazars.

Catalogs of blazars can be used to identify new blazars by searching for objects with blazar-like properties and by cross-matching catalogs of blazars with other catalogs of astronomical objects.

Catalogs of blazars have been used to make a number of important scientific discoveries, including the discovery of the blazar phenomenon, the identification of new blazars, and the study of the evolution of blazars.

Future research on catalogs of blazars will focus on compiling more comprehensive catalogs of blazars, studying the evolution of blazars in more detail, and using catalogs of blazars to identify new blazars.