How can I improve my website authority?

Let me first introduce you what is website authority. It is a metric or number from SEO tool providers. It measures the relative strength of a site’s backlink profile compared to every other site in their index. Each and every major SEO tool has this measurement, however its name and the way it’s determined varies in every one. Website authority metrics runs on a scale from 0–100. 
Now, it’s important to understand that the scale for website authority or Domain Rating is logarithmic. That means it’s much more challenging to reach 60 or 70 from 9 or 10.
How Website Authority Calculated?
Before trying to improve your website authority, you first need to know how the Domain Rating is calculated. Here three major things enlist below that impact Domain Rating. 

1. The number of websites linking to you: In Ahrefs, there is a metric called referring domains. This is the number of websites that link to a page or website. The tool take ‘followed’ links into account in our Domain Rating calculations. Links with UGC, sponsored, and nofollow attributes won’t improve Domain Rating. Also, subsequent links from the same website won’t improve a site’s DR since we count referring domains and not backlinks.
2. The DR score of linking domains: Anyone can get thousands of links from a bunch of low-quality sites. That’s why tool also take into account the Domain Rating score of the linking site when calculating DR. This means that backlinks from websites with high DR scores tend to increase your Domain Rating more than those with low DR scores. That’s an interesting point to know. It means that as the DR of a linking website increases, so can yours. The takeaway here is that it pays to build links from sites that show potential, even if their DR scores are quite low at the time. To check potential first, check their content. If they’re publishing high-quality stuff, they’re more likely to attract high-quality links naturally over time. Second, check their link growth in Ahrefs’ Site Explorer. If there’s a slow and steady upward slope on the referring domains graph, chances are things will continue in that direction and their DR will grow over time.
3. The number of sites each referring domain links to:  When you build two ‘followed’ links: one from The Guardian and one from IMDB. Both of these sites have identical DR scores, but which link would increase your Domain Rating the most? Answer is It depends on the number of sites they each link to with at least one followed link. The more unique websites a site links to, the less so-called “DR equity” it can pass.

How to increase website authority?
Build more ‘followed’ links to your site and your Domain Rating will increase. It’s as simple as that. Just keep in mind that if the site you get a link from has a low Domain Rating score itself, or links out to lots of websites, the increase in Domain Rating may be negligible. 
It’s also important to note that building links to random pages won’t always help increase your rankings or organic traffic. As that’s almost certainly your end goal, you should focus on building links directly to the pages that you want to rank in Google. That will have a bigger impact on organic traffic and rankings than simply “increasing Domain Rating.”
Here’s how to indirectly increase your website (domain) authority in a ‘meaningful’ way:

1. Create content that people want to link to
2. Pitch relevant and authoritative websites
3. Use internal linking to improve the ‘authority’ of important pages