Domain age refers to the length of time that a website has been registered and active. In SEO circles they often talk about aged domains, i.e. web domains that have more domain age.
Domain age conveys trust to website visitors and to the search engines.
Two factors are considered in the age of a domain name.
First, is the length of time that a domain has been registered.
Second, is the age of the website in regards to how long that it has been active, or how long that it has had crawlable content on the web