We’ve all heard of these. Web filters are applications that limit access to certain content on the web, possibly because it is harmful, not appropriate, or not secure. Different filters will regulate different types of content. Many businesses use filters to prevent employees from doing non-work-related things on their computers. School and public libraries apply these filters to their public access computers due to the Children’s Internet Protection Act (CIPA) passed by Clinton in 2000; these filters are aimed to protect children from harmful content.
The primary concern with such filters is that they often do not do their job, blocking content that should not be blocked but allowing content that should be. While in some cases the software company arguably does these things intentionally (see the AOL example), most other times the software simply is not intelligent enough to actually know what sites are against CIPA regulation and what sites are not.
Certainly, these filters have social repercussions. On the one hand, they can be beneficial in that they can prevent children from viewing websites that may be violent, pornographic, or otherwise harmful (NOTE: not everyone will agree that this is beneficial; some argue this should be determined by the parent, not the government or local library or some filter vendor). On the other hand, they can limit a person from viewing legitimate information on the web, information they should be allowed to access based on First Amendment rights. As such, they actually have the ability to limit free and open access to information.