One of the factors Google considers when evaluating your website is how many inbound links it has. Inbound links happen when other sites link to you. One of the ways to do this is by linking to other sites. When you link to other sites and they see traffic from your site, they will take notice. Webmasters pay attention to these things. Typically these webmasters will visit your site and if they like what they see, they may link to you. This will give you direct traffic when people click on that link. It will also show Google that you have another inbound link, moving you ever closer to a better search engine ranking.