To travel to the USA you need a visa or an approved ESTA. You have to apply for an ESTA at least 72 hours before your departure en you will be charged for this. Recently the price for an ESTA application was raised by 50%.
If you meet certain requirements you don’t need a visa to enter the USA, but only an approved ESTA application. Previously an ESTA application cost $14 per application. Since 26 May 2022 the prices were raised and it will now cost you $21 per approved application. If you application is declined, you only pay $4 administration cost.
More information on the requirements for an ESTA can be found here: ESTA
On the official page of the Department of Homeland Security you can apply for an ESTA: