去美国一定要申请ESTA吗？

在天巡上订美国境内机票，提示如下，ESTA是必须申请的吗？毕竟要花14刀。谢谢！！！
PLEASE REMEMBER:
All passengers flying to the United States or transiting in the United States must have an authorization of the ESTA (Electronic System for Travel Authorization) in their possession.

Authorization is obtained by filling out the form on the Electronic System for Travel Authorization website: https://esta.cbp.dhs.gov/esta/esta.html and this must be done AT LEAST 72 HOURS PRIOR TO DEPARTURE.

Remember that without the ESTA's authorization, the airline will NOT ALLOW PASSENGERS TO BOARD THE PLANE.

Should you have any further queries, please contact our Customer Service.