US citizens traveling to Europe will need to apply for an ETIAS  visa (European Travel Information and Authorization System), a new travel authorization for Europe that will come into effect as of 2021.
The  ETIAS visa for US citizens is meant to maintain a high level of international security. To obtain the visa for Europe, US citizens will need to have a valid passport, a credit or debit card, and an email account.

At the moment, there is no EU visa for US citizens visiting Europe for periods of less than 90 days. However, this will change from 2021 as US citizens traveling to Europe will need to obtain an ETIAS visa.
The ETIAS visa shall be valid for 3 years during which period US citizens may enter any of the Schengen Zone European countries as many times as necessary.
When applying for an ETIAS visa applicants must ensure that the passport used must be valid for 3 months beyond the period of intended stay.
The ETIAS visa for Europe must be paid in advance through secure online payment.