The Internet is a vast, sprawling world of resources, offered by millions of connected computers and servers. All it requires is a standard protocol, and each site or server maintains its own index, if any. There is no centralized management or authority to appeal to if something undesirable is found.
Companies such as Google, Yahoo, and Microsoft put forth considerable effort to create automated indexes, what we call search engines, so we can reliably find what we are looking for. Without such engines and their ability to find material, we would have little way to locate information unless we already knew where it was. Anything unknown is effectively invisible.
The majority of the information on the Internet is targeted for adults, since it is created and maintained by them. This enables us to have wide-ranging and diverse conversations about all topics.
Unfortunately, some of that information is not presented in a way that is friendly to children, whom may lack context to fully understand what they are viewing. While there are specific child-friendly sites on the internet targeting specific age groups, there is no thorough way to protect a child from the Internet as a whole.
At home, parents can try to install and maintain filters that can block material they find objectionable, and some schools do the same. While there are proprietary software packages that may work for Windows and Apple OS X, there are few to none for free platforms such as Linux. However, on an internal home network there are ways to direct all requests through a central server that can monitor and attempt to restrict access to known sites. Sometimes just the awareness that access is being monitored can be enough, and these techniques work for all software platforms. They do not work reliably when HTTPS (encrypted) sites are accessed, since the encryption hides the request from the monitoring software.
To further complicate matters, Internet access is largely ubiquitous, and children are persistent. Even if it involves going to a friend’s house, to a public library, or even a coffee shop, it’s largely impossible to completely block their access.
In closing, there is no completely reliable way to protect children from the Internet. With that in mind, it is useful for parents to understand that their children will almost certainly learn about topics that parents may find uncomfortable, and will instead have to keep an open dialog to always be aware of what their kids are accessing and what they’ve found to provide an educational context.