When you see a clickable word or phrase in a webpage, that's the anchor text. It's the visible, highlighted text that links to another page. For example, in "Read our complete SEO guide," if "complete SEO guide" is the link, that phrase is the anchor text.
Good anchor text is descriptive and keyword-rich. Instead of "click here," use something like "beginner's guide to Facebook marketing" — this tells both the reader and Google what the linked page covers. However, don't overuse the same keyword anchor text repeatedly, as Google may flag it as manipulative. Keep it natural and varied for the best SEO results.