A catalogue of cataclysmic variables from 20 years of the Sloan Digital Sky Survey with new classifications, periods, trends and oddities.

Abstract We present a catalogue of 507 cataclysmic variables (CVs) observed in SDSS I to IV including 70 new classifications collated from multiple archival data sets. This represents the largest sample CVs with high-quality and homogeneous optical spectroscopy. have used this derive unbiased space densities period distributions for major sub-types CVs. also report on some peculiar CVs, bouncers exhibiting large changes accretion rates. 59 periods, 178 unpublished spectra 262 or updated classifications. From spectroscopy, we identified 18 systems incorrectly as literature. discuss properties 13 CVS, identify small set eight that defy standard classification scheme. use investigate distribution different CV sub-types, estimate their individual densities, well entire population. The includes 14 bounce candidates. variability across Hertzsprung-Russell diagram, highlighting selection biases variability-based detection. Finally, searched for, found tertiary companions anticipate extensive material included Supplementary Data will be useful range observational population studies