Visitors of countries participating in the Visa Waiver Program (VWP) who wish to come under visa waiver may be granted permission to enter for 90 days only and may not extend their stay. Currently, 36 countries participate in the Visa Waiver Program. The list of VWP countries and requirements, including Electronic System for Travel Authorization (ESTA), can be found on the US Department of State website at http://travel.state.gov/visa/temp/without/without_1990.html.
If you do live in a visa waiver country, you do not need a visa.
If you do not live in a visa waiver country, you need a visa.
If you require a visa to attend NIPS at Lake Tahoe, you should start your application as soon as possible.
Here's the link to the US Consulates/Embassies worldwide. Usually one will set a visa appointment in your home country. It's a good idea for individuals to start early in case there are lengthy visa delays, sometimes due to security checks.
See the US Department of State's information on Visitor's Visas for Pleasure and Business at http://travel.state.gov/visa/temp/types/types_1262.html
It may also be useful to read the National Academies advice on attaining a visa.
A generic invitation letter is provided for you after you have paid for conference registration. If you need a customized letter for your visa, you must have a paper accepted at NIPS 2013 and you must have paid for your registration.
To request a custom letter, email us
Include your name, complete mailing address, and the title of your paper. A pdf of the letter will be emailed to you; if you need the original, signed letter, you will need to provide a Federal Express account for shipping.