Everyone has probably heard of "parental controls", they are the mechanism whereby you can lock down the browser on your computer to stop minors from accessing unsuitable material on the Internet. They work by reading the PICS labels embedded in the page headers of websites, if the site is clean then your children can see the site and if not they cannot.
The problem being that many unsuitable sites do not declare that they are unsuitable therefore the only way these things can work is that they must block every site that does not have a clean PICS rating
PICS labels can also tell the search engine robots what type of content you have on your site and even if most of the public do not have parental controls set up they may also not get to visit your site because some search engines will not list unrated sites.
In addition to acting security guards to prevent hackers from accessing internal corporate or academic networks, Proxy servers also provide "parental controls" for companies and other institutions like universities and schools and they can also be set up to ban access by their employees or students to all unsuitable sites.
So if you have a business or information website if you do not have PICS labels it is unlikely that you will have many users from big business or academia
There are a number of organisations that provide PICS labelling services and before you panic it is usually FREE. The method of labelling and verifying your site can be different with each one so you have to read the instructions on their websites carefully. It is also beneficial to register with more than one service.
Here are a few PICS service providers
You can also write your own labels in accordance with the agreed protocols, you can find out more about this at W3C-PICS