it is the service which generally allows Encryption in Transit across AWS services

Create store, renew SSL/TLS X.509 certificates that work with single domains, multiple domains and wildcards.

It integrates with

ELB

CloudFront

Elastic Beanstalk

Nitro Enclaves

Cloud Formation

You can

create Public Certificates signed by AWS CA

create a Private CA with ACM and then issue private certificates

import certificates from other issuers