This is the term given to the use of keywords within text content on website pages and contained within the links to websites. Keywords are vital for both marketing and getting the message across to site visitors to tell them what services or products you offer.
Think of it this way: these words tell both website users and 'search engines' what you have to offer!
It sounds simple and obvious but its vitally important to ensure that you use relevant keywords on your webpage and in the text that links to your website.
Whenever you can its wise to request that a variety of keywords are used in the anchor text of website links. If you use the same keyword 'all the time' this is like telling potential customers / search engines that you only have one product or service and in the real world, this would be untrue for almost every business.
Remember this when looking at your website marketing, ensure that all you products and services are used with regard to keywords in links to your website.