Anchor text mush be related to your keyword. If your Keyword is Search Engine Optimization, your anchor text should be "SEO"
Keywords are the words that are present in the web page content, where as anchor tags are the main menu links that will take you to its respective page. Anchor tags works like back-links as a do follow link, if you write no follow to anchor tag then it won't be calculated as a back-link. We can add links to keywords which are present in the content. anchor tag consists hyperlinks to other pages.