Hepatitis C is caused by the Hepatitis C virus (HCV). In the scientific system that names and organizes viruses, the Hepatitis C virus is part of the "hepacivirus" genus in the family "Flaviviridae". There are seven major types of HCV, called "genotypes". In the United States, the first genotype of HCV causes 70% of all cases of Hepatitis C (or 7 out of every 10); the second genotype causes 20% (or 2 out of every 10); and each of the other genotypes causes 1% (or 1 out of every 100 cases). Thr first genotype is also the most common in South America and Europe.