Domain Name Whois - It is an Internet utility program that obtains information (such as owner and contact info) about a Domain name or IP number from the database of a domain name registry. it can be used to find the validity perion of the domain. If the search result returns "No match", the domain name is probably available, and you can apply to register it.
Whoever controls the email address associated with a domain name Registrant controls that domain name. Make sure that you control that email address, and keep controlling it.