WHAT? WHY? AND HOW? OF ANCHOR TEXT

WHAT? WHY? AND HOW? OF ANCHOR TEXT: "The most important purpose that an Anchor Text Serves is that it tells the Search Engines what the page is all about to which it is linking and this has great SEO value - that is this helps greatly in improving positions in SERPs(Search Engine Result Pages). It helps in off page optimization of the page for a particular keyword phrase for which you are trying to rank well in SERPs."