This link building strategy consists in submitting your website to both human and automated website directories, they are just like the yellow pages phone book but instead of commanding outrageous monthly and yearly fees and dues they are free to submit to, most of them anyways. The ones that charge a fee are usually not to be trusted unless you are an experienced SEO/SEM online marketing expert with web design experience that is knowledgeable enough to tell the good directories from the bad ones. But still some tools are available to choose what directories to submit your site to and witch ones to avoid.Common tools included but are not limited to the Firefox no follow extension, Alexa Tool Bar and Google toolbar. Some are link farms and could possibly hurt your website so one must be very careful to what directories to submit the site. For that reason it is usually advisable to stay away from automated directory submission services and automated schemes. Best to submit one by one after careful evaluation of the website directory's reputation and credibility. Some very safe directories to submit to are the ones that are approved by DMOZ, this means that they are also backed by Google. While they are safe to submit to some very strict submission guidelines must be met and applying the wrong way could get your site banned for re-submitting again for months or even years. So then again, it is recommended to use the services of a human directories submission expert to take care of this very delicate link building strategy.