The US B1/B2 tourist visa is a non-immigrant visa issued by the US government to foreign nationals who wish to temporarily enter the US for purposes including: tourism, leisure, visiting family, medical treatment, attending non-commercial events, or short-term business trips.
The B1/B2 visa is typically issued as a multiple-entry visa, valid for up to 10 years (depending on the application). The length of stay per entry is determined by the CBP (US Customs and Border Protection), with a maximum of 6 months per entry.