Many of the more specific sub-categories are named after the first known or prototype of the class. Pulsating variables include the Cepheid variables whose period from maximum to minimum light changes like clockwork. The relationship between their period and luminosity has made them yardsticks to measure stellar distances. Miras, named after Omicron Ceti, are long period pulsating giants. It can take hundreds of days for a Mira to go from minimum to maximum magnitude.
Irregulars are slow changing with irregular changes in brightness.
Semi regulars are somewhat periodic, but show irregularities in their periods. RV Tau type stars are pulsating supergiants that exhibit alternating brighter and fainter maxima in their light curves. Eruptive and cataclysmic variables are very unpredictable and come in a great variety. Orion type stars are young stars embedded in nebulosity. T Tau types are similar to Orion stars, but have different spectral characteristics.