White Lists And Black Lists Filtering The Internet
If you put aside the various technologies involved in content filtering, you have two basic choices use a white list or a black list. It's actually quite simple a black list is a list of URLs or web sites that you decide should not be viewed. This could apply to your county, workplace, ISP or even just your own home - the software is readily available to implement this.
However as anyone who has tried will testify to, it's actually quite hard to completely implement a black list. Even with the most sophisticated content filters on the market if you use certain online anonymity technology you can bypass the majority of these controls.
In fact if you really do want to control access to the Internet, the most effective way is to implement a white list. So instead of blocking you allow access to a web site, that is the only web sites allowed are the ones that have been approved. It's the direction many countries like China, North Korea and Iran are heading and it's not hard to imagine what that process does to the Internet.