Internal Link Structure
The internal link structure of your website is literally the structure of all the internal links of your website.
An “internal link” is nothing more than a link that originates on one page of your website and points to another page on the same website. By page, I mean webpage, not WordPress page.
In WordPress, both pages and posts create webpages that are HTML and are addressed via a URL.
The fact that the link never leaves your website is what makes it “internal”.
The importance of your internal link structure is you use it to raise the authority of your best posts and pages.
What tends to happen over time (and I’m as guilty of this as anyone) is over time, as you create internal links for your blog posts, you create a web-like internal link structure.
While what you want is an internal link structure that is hierarchical in nature.
The hierarchy gives authority to pages in a more structured or focused way.
A clean and well-optimized internal link structure is no magic bullet. It takes conscious effort and takes times, but it helps rank your most important pages and posts.SEO Needs Link Building