Internal linking refers to the practice of linking to other pages within the same website using hyperlinks. It helps search engine crawlers discover and index content, establish website hierarchy and authority, and distribute link equity throughout the site. However, improper internal linking structures can cause indexing issues if important pages are not properly linked or orphaned from the website's navigation. Search engine crawlers may struggle to access and index content that is buried deep within the website or inaccessible through internal links. To address internal linking issues, webmasters should conduct regular site audits to identify orphaned or poorly linked pages, optimize anchor text and link placement for relevance and usability, and use HTML sitemaps or navigation menus to provide clear pathways for crawlers to access all content on the website. They can also use tools like Google Search Console to monitor internal link errors and crawl efficiency.