The more search engines, websites and directories you have linking to your website, the greater opportunity you have of reaching an audience. Some search engines, including Google, review, assess and score the inbound link (IBL) popularity and relevance of the external websites linking to yours. The more relevant the websites content is and the higher its own position in the search engine listings, the greater the score credited to your website ranking.

It is therefore important to ensure that the content and relevance of the websites linking to yours is similarly themed to:
(A) Ensure that you are communicating with your target audience
(B) Avoid being penalised by the search engines for trying to artificially generate the perception of website popularity.

There is no value in having a florists website linking to your mobile phone site for instance, in fact this can prove counter-productive.