A 'walled garden' refers to a controlled web browsing environment.
Services, like Aol's parental controls, are a perfect example of
a walled garden: this is where the ISP restricts the user from browsing
adult related areas of the World Wide Web - like pornography sites.
Walled gardens are also a must have for most high school networks
- which need to restrict students from accessing such websites.
Of course some walled gardens are not so popular: countries like
Iran have been criticised for not allowing their citizens full access
to the World Wide Web - by restricting access to social networks