Your domain name is the internet address of your website, and also part of your email address (if you are using branded email, and you should be.)
Over the years, we have seen a startling number of scenarios where web design clients have absolutely no idea how to access their domain name or do not have control over the domain. Do not let this happen to you.
Figure out where your domains are registered. This is likely to be somewhere like NameCheap, GoDaddy or Network Solutions, and there are hundreds of others as well.
Consolidate your domains into an account into one account that you have access to. If your brother-in-law, web designer or IT friend registered a domain for you in their name, ask them to help you transfer it to your account.
Carefully consider your account contact information. Use an email address that is yours and not tied to an employer or an internet service provider. People often forget their login credentials and need to retrieve them by email. What if you change jobs or switch from Comcast to FIOS? You will no longer be able to access that email address and will be out of luck. Domain registrars will also send renewal reminders and important notices to this email address.
Once you have yourself organized, create a document with your domain information and your pertinent contact information and print out a hard copy to put it with your other important documents as a backup.
Brief a trusted family member or a friend on where they kind find this information if you are not available.
We worked with a client that had an ecommerce site that provided significant revenue for the business. While the company had a number of employees, the CEO was the only person with access to the domain registration and it was associated with an email account he no longer had. To compound matters, at the time of the domain renewal, he was in Europe and very difficult to contact. Their site went down and stayed down until he could return, prove ownership, and renew the domain.
Your domain name is the key to your online business identity. Take good care of it!