A walled garden means 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 web like pornography sites. Walled gardens are also a must have for most high school networks. Of course some walled gardens are not so popular, countries like China have been criticised for not allowing their citizens full access to the web.