Classical swine fever virus (CSFV), belonging to the genus Pestivirus of the family Flaviviridae and species Pestivirus C, is the aetiological agent of a disease called classical swine fever (CSF) or hog cholera, which is a devastating transboundary disease of pigs across the globe. Besides domestic pigs, the disease has been reported from wild pigs, and pygmy hog (Porcula salvania) and wild boar are also reservoir hosts. The CSFV size ranges from 40 to 60 nm, and the genome of the virus consists of a single-stranded, positive-sense RNA. Based on sequence analysis, 3 genotypes and 14 subgenotypes of CSFV have so far been reported, and a shift in the historical genotypes 1–2 has been observed in the recent past. Although many countries are now free from CSF, the disease is still widely prevalent in most of the South American, Asian and South East Asian countries possibly due to high pig population, low vaccination coverage and poor biosecurity. The virus spreads in different ways, and after entry into the susceptible hosts produces various clinical manifestations. The peracute form of CSF has disappeared, while acute form occurs commonly in younger animals and chronic form is more common with reports of absence of clear symptoms in adult animals. Confirmatory diagnosis of the disease is to be made at the early stage to prevent its spread and control of CSF is important to sustain pig production to meet the growing demand of pork in different parts of the world.