"Whois" is a public system for querying registry databases.

Whois means "Who is...?" It is the domain name search feature on the web for Top-Level Domain name registries. The whois program accesses the information databases to return information on the owner, administrator, technical contacts, and name servers for a registered name. Additionally, it will often tell the registrar company and the date the domain name was first registered. Sometimes it will return an answer like "record not found" or "the name is available."  This usually means that the name has not yet been registered. 

As a condition for registering a domain name, you must agree to allow your own contact information (name, address, phone number, email address) to be included in the domain name record available by whois.  This requirement is system-wide in the registry.  There is no way your domain registrar can prevent it from being displayed.

This is why you should carefully consider how you want your information displayed.  For instance, you may wish to use your company's phone number for a domain registered to the company you own, rather than your private home telephone number. 

Also, it is best for the long term ease in controlling your domain name to supply a permanent address, phone and email.  Consider the scenario of a college student using a dormitory address and school email account.  When changes to the domain name record are requested a year later when the address and email are no longer valid, or at renewal time when we can no longer contact the domain owner or administrator, a lot of extra work could be involved. It could even result in the loss by expiration of a domain name.

So, plan ahead. If your email account or address changes, please notify your domain registrar far in advance of the actual change as possible by emailing them.