Anchor text is the text the user will read before clicking on a link, therefore, the link text needs to be relevant to the page that you’re linking to.
Anchor text is not only used for user experience reasons to give some idea of the relevancy associated with clicking that link but from a search engine perspective too, both internally and externally.
The search engines often use anchor text to determine what keywords your page should be ranking for in the search results. If you have a lot of external links pointing to your homepage with the anchor text of: seo blog, Google will start to assume that your website is somewhat relevant to this search query and will take that into consideration with their ranking algorithms. It’s the same principle when adding internal links, you’re effectively telling Google what the page is about via anchor text. This helps with the ranking process.
However, ensuring that you use different combinations of anchor text is important, as having too many external links using the same anchor text may be considered manipulation in the eyes of Googlebot. Therefore, reducing your sites overall authority that may result in a Google penalty.