Hey! Domain Authority (DA) is a score made by SEO tools like Moz and not by Google. Google doesn't use it to rank sites. BUT a DA 90 is like a titan of the internet, we are talking about New York Times, Forbes or Nike level. These sites have immense trust and power because they have been around forever and have millions of natural links. That's why a backlink from them is so valuable, it's like a superstar endorsement. Honestly I wouldn't get too hung up on the DA or DR number and it's pretty much impossible for a normal site to reach that giant status. Secondly these metrics are also just a business for the SEO tool companies, the real goal is much simpler, just focus on building a great site with helpful content that naturally earns links, and always avoid shady black hat tactics that get penalized very fast by Google. Build real value and not just a number.