  We describe the current status of CATS, a publicly accessible database
(web-server http://cats.sao.ru) allowing one to search in hundreds of catalogs
of astronomical objects discovered all along the electromagnetic spectrum. Our
emphasis is mainly laid on catalogs of radio continuum sources observed from 30
to 15000 MHz, secondly on catalogs of objects such as radio and active stars,
planetary nebulae, HII regions, supernova remnants (SNR), pulsars, nearby
galaxies, AGN and quasars. CATS also includes the catalogs from the largest
extragalactic surveys, like NVSS, FIRST, WENSS, VLSS, TXS, GB6, SUMSS, IRAS,
2MASS, SDSS, ROSAT, PGC, MCG, etc. In 2004 CATS comprised a total of $\sim10^9$
records from over 400 catalogs in the radio, IR, optical and X-ray windows,
including most of RATAN--600 catalogs. CATS is being expanded and updated, both
with newly published catalogs as well as older ones which we have created in
electronic form for the first time. We describe the principles of organization
of the database of astrophysical catalogs and the main functions of CATS.
