Do I have to pay for an ESTA application when travelling from the UK to the USA?

I don't understand the application process and if I have to pay or not?

Thanks!

No. Just fill in the online form

No you don't have to pay if you are completing the online form and submitting directly to US immigration. If you are using a third party, you may have to pay.

The online form just requires your passport details. You can enter your flight details if you have them. Once you have ESTA approval, you do not have to complete another one for two years.

Visit the website for the US embassy in the UK and follow the links.