You can make it easy for users to find your Google services such as Gmail or Drive, or a web site you build with Google Sites, by customizing the web address (or URL) they type in their browser. That way, all they have to type is mail.yourdomain.com, or www.yourdomain.com, or just plain old yourdomain.com (using, of course, your organization's actual domain name).
Customize a Google service address
Create easy-to-remember shortcuts to users' services such as Gmail, Drive, and Calendar. With a custom web address, for example, users can type simply mail.yourdomain.com to access their Gmail account instead of the longer default address mail.google.com/a/yourdomain.com.
Customize a Google Site address
Customize an address to a web site you build in Google Sites so it doesn't include sites.google.com/a at the beginning of the address. This is how you create the address www.yourdomain.com for your organization's public web site.
Enable your "naked" domain address
Allow the public to also access your www.yourdomain.com web site by typing simply yourdomain.com—that is, the "naked" address without the w's.