Once a domain expires, the registrar will allow around 30 days for the original owner to renew it. This period depends on the registrar and can range from 2 weeks to a whole year. Once this period is over, the domain enters the "Pending Delete" status, during which it cannot be renewed, purchased or modified in any way. Once the Pending delete status is over, the domain is dropped back into the available pool, and can now be purchased by anyone.
The better quality links (From Google, Wikipedia) that a website has the higher will be its domain authority. New websites start with a ranking of one, and as the number of links increase the domain authority rises. For example, a sports website that has links to sports newspapers and sports reporting sites will have a higher domain authority than a sports website that only has links to other sports and sports blogging sites.
We do not only have Expired Domains, but you can also find lists of Deleted Domains for a lot of TLDs. Deleted Domains or Dropped Domains are available for registration and can be picked up for just the normal regfee at your preferred domain registrar! All Domains have the typical SEO relevant data, like Number of Backlinks, Archive.org Birth Date and a lot more.