An administrator is building a Lightning app and sees a message that a My Domain...

My Domain is a feature that allows administrators to create a custom domain name for their Salesforce org that replaces their instance URL (such as na35.salesforce.com). My Domain provides benefits such as improved security; enhanced branding; faster navigation; access to Lightning components; etc. However, one of the considerations when enabling My Domain is that it changes how users log in to Salesforce - instead of using their instance URL login (such as login.salesforce.com), they have to use their My Domain login (such as mydomain.my.salesforce.com). This applies to all internal and external users who access Salesforce via web browser or mobile app. References: https://help.salesforce.com/s/articleView?id=sf.domain_name_overview.htm &type=5