Domain Authority (DA) is a number that is allotted by MOZ and it shows the ranking of a specific website on Search Engine Result Pages.
It ranges between 0-100 whereas this number depends on various factors.
The factors
for the determination of DA includes Back-linking and its quality, website speed, internal links as well as the overall performance of the said website.
Talking about the Domain Authority checker, it's a tool that checks the domain authority of a domain.
These tools are usually available online for free. Users use this tool to check the Domain Authority while getting backlinks from the said domain.
However, getting the backlinks
from the higher DA domain will help you in increasing your site's DA.
You should know that Google won't use the DA in its algorithms to rank a website on SERPs.

Author's Bio: 

Fahad Shehzad writes SEO articles for online business marketers and SEO tools users to make their Google rankings surge. His articles have appeared
in a number of websites i.e., eLearning Industry, and Inside Tech Box. He contributes articles about digital marketing, SEO techniques and tech regularly to