Internal links are the cheapest SEO win you have. They help Google find new posts, show which pages matter most, and keep readers moving through your site. The problem is doing it consistently once you have 50, 100 or 500 posts. Nobody remembers what they wrote two years ago.
That is where internal linking plugins help. They suggest relevant links as you write, find orphan posts, and, in some cases, add links automatically. This WordPress internal linking plugins guide compares the best ones and explains how to use them without turning your posts into link soup.