The US visa waiver program allows citizens of the UK, Australia, New Zealand, the eurozone and several other countries including Japan to enter visa-free for a stay of up to 90 days. Nationals of other countries should contact their nearest US Embassy or Consulate for details on requirements and costs.
Health and Safety
There are no specific vaccination requirements, although it’s recommended that the usual shots such as tetanus are up to date. Statistically, New York is the safest of all the US’s large conurbations, due to the police presence in most of the major tourist destinations and busy transportation hubs.
Purse-snatching can be a problem, in restaurants as well as on the streets and subway, so leave anything of value in your hotel safe. Muggings are rare, but it’s common sense to be aware of your surroundings especially at night, and avoid Central Park after dark.
Airport-style security is a feature at most museums and attractions nowadays, but it’s efficient, fast and polite. If you find yourself in an unsafe area at night, grab a cab, and if you’re the only person at a subway station, stay within eyesight of the clerk. Locals and city police are friendly and approachable for the most part if you’re lost, but other than that, they'll mostly ignore you.