These are used to authenticate to outside systems and need certain authentication fields like passwords, access tokens or refresh tokens. Authentication is needed for sources such as Google Docs, Office 365, and Salesforce.
Authentication connections are used by Integration Connections to connect to the source repositories.
Authentication connectors are reusable. Instead of writing the auth configuration into every repository / output connector, we can set the authentication configuration in one authentication connector and use it with multiple connectors. For more information on specific Authentication connectors, click the link for the software below that you want to connect to.