Travel Authorization can only be applied for by a visitor holding an electronic passport from one of the Visa Waiver countries. Any other visitor must still apply for a B-1 Business Visa or B-2 Tourist Visa in advance. A Travel Authorization permits the US visitor to travel to the United States by air or sea. The authorization is only related to "permission to travel to the United States" whether it be to visit or transit through to another destination. An approved Travel Authorization does not guarantee entry nor transit through the United States. If you are planning to transit or visit the United States within the next 6 months you are recommend to apply already now. If you travel to the United States and are denied entry, you will never be able to enter the United States on the Visa Waiver Program again and must in the future apply for a B-2 Tourist Visa.
Yes. A traveler planning to transit through the United States en route to another country must also obtain an approved travel authorization in advance. When he or she complete the ESTA application, the words "In Transit" and the final destination should be inserted in the address field under the heading "Address While In the United States".