Electronic System For Travel Authorisation (ESTA) for VWP travellers to the USA
The US Department of Homeland Security (DHS) has introduced a new system, known as the Electronic System Travel Authorisation (ESTA) which changes the entry procedures for travellers to the USA under the Visa Waiver Programme (VWP).
Since 12 January 2009, if you are travelling under the VWP you must obtain electronic travel authorisation prior to boarding your flight to the United States. If you do not receive travel authorisation prior to departure you may be denied boarding, experience delays or be denied admission into the United States. You can apply online anytime prior to travel, but it is recommended that you apply no later than 72 hours prior to departure.
ESTA requires submission of data that is currently provided by travellers arriving at US ports of entry on the green I-94W landing card. ESTA is mandatory for all Visa Waiver travellers and over time the old, green I-94W forms will be phased out, however both forms are currently required to be completed until further notice. No more information is being requested under ESTA than is currently required on the I-94W.
If you are planning to travel to the United States, you must register with ESTA before your departure, preferably at the time of booking. If your registration is successful, it will be valid for multiple entries into the United States for a period of two years or until the date on which your passport expires, which ever comes first. If you plan future trips or if your destination address or itinerary changes after authorisation, you can easily update that information through the ESTA website. For further information visit the Foreign and Commonwealth Office