This means that a good database of acceptable URLs would number in the millions, and soon billions. Plus, the Internet's rapid growth far outpaces the realistic ability of a person or organization to screen new sites, and add the majority of them to the pass-through list. A pass-through list certainly affords the greatest restrictions by limiting the sites available. But by cutting out such a large percentage of the Internet, you are no longer surfing a vast ocean of sites - you are paddling in a virtual pond. Possibly the most cumbersome and debated method of filtration is the process of rating sites.
Several groups offer ratings systems and ask webmasters to submit their sites for review.
Then, surfers choose a ratings level and hope that their target sites have been rated. But the problems involved with this method have already rendered it useless to many people. First, there is the problem of compliance. Web sites must be submitted to a certain group for review. The odds of getting a significant percentage of the population to voluntarily submit to this process are very low indeed.