Does Singapore passport need a visa to go to the United States? How long can I stay?

Singapore passport requires a visa to go to the United States. 90 days visa-free.

Visa refers to the procedure of endorsement and seal of passports or other travel documents held by domestic or foreign citizens by the sovereign organs of a country to show that they are allowed to enter, exit or transit. It can also be said that it is an endorsement certificate issued to them. Generally speaking, a visa is a document issued by a country's entry-exit administration (such as immigration bureau or its embassy or consulate abroad) to approve the entry of foreign citizens.