A USA ESTA (Electronic System For Travel Authorisation) is similar to a visa, but no stamp is affixed in your passport. When the ESTA is issued it is valid for 2 years or until your passport expires and will allow multiple entries into the USA.
Passport holders from the participating countries of the Visa Waiver Program can visit the United States for a stay of up to 90 days for tourism, business, medical purposes, and recreational studies by applying for an ESTA.
If your USA ESTA is approved you are entitled to travel to the USA under the Visa Waiver Program. An approved ESTA does not guarantee admission to the USA, it will be determined by the officers at the point of entry. If your ESTA is not approved you are not entitled to travel to the USA under the Visa Waiver Program. You may be able to obtain a visa from the USA Consulate.
You will be able to apply under the Visa Waiver Program if you are a citizen of one of the Visa Waiver Program countries as follows:
If you have already completed the application form earlier and just want to make a payment, please proceed to the USA ESTA payment page.