Google finds it easier to crawl and discover new pages

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As mentioned above, any page on your site should ideally be accessible within three clicks or less from the homepage. If a page on your site doesn’t have an internal link, Google’s search engines job seekers database won’t see it. Ensuring that the web pages you want to rank are easily discoverable by search engines , and therefore crawled and indexed, is a critical first step to making your site more visible in the SERPs .

Signal Relevance and Context
Google also relies on the anchor text of internal links to understand context and relevance to various search queries. If the anchor text doesn’t match the content of the page it’s linking to, Google is less likely to trust that page or rank it higher in the SERPs for related keywords. However, using the right anchor text can help Google more fully understand what the page you’re linking to is about. That’s why using your keyword in the anchor text is so important when building links.

anchor text for internal linking in on-page SEO
PageRank Distribution
Internal links also help distribute PageRank across our sites. PageRank is Google's proprietary metric that reflects the popularity of a web page, measured by the total number of links pointing to it. Every time a page links to another, it passes on some of its PageRank, or link equity.