The text used to form a link is commonly referred to as anchor text, e.g. if you have someone linking to you with the text 'homes for sale', the anchor text for that link would be 'homes for sale'.

When submitting to directories, the titles entered for a site are used as the link text (anchor text) by the directories. Therefore titles can be manipulated in order to target specific keywords or key phrases with which you'd like directories to link to you. Links with chosen anchor text allow the search engines to classify the relevancy of your website. This, in turn, can help your website rank high for the targeted keywords / key phrases on the search engines.