Search Engine Optimization. To get a bit more visitors to the site to sell more things and / or services.
If thats not selling then I do not know what is and I am getting the impression this point is being missed by a massive section of the S.E.O industry. Too many S.E.O firms are so concentrated on the Ultimate Prize of a page one listing on Google that they forget that from the clients viewpoint its only stage one of a wider process. Maybe this is because of the proven fact that lots of S.E.O staff aren't essentially that great at the copy writing facet of the business. Good copywriting at that point is vital to ensure that this is the link that grabs races interest. Modules extend the utility of the CMS core.