OVER the next decade, approximately five billion people will become connected to the Internet. The biggest increases will be in societies that, according to the human rights group Freedom House, are severely censored: places where clicking on an objectionable article can get your entire extended family thrown in prison, or worse.

The details aren’t pretty. In Russia, the government has blocked tens of thousands of dissident sites; at times, all WordPress blogs and Russian Wikipedia have been blocked. In Vietnam, a new law called Decree 72 makes it illegal to digitally distribute content that opposes the government, or even to share news stories on social media. And in Pakistan, sites that were available only two years ago — like Tumblr, Wikipedia and YouTube — are increasingly replaced by unconvincing messages to “Surf Safely.”

The mechanisms of repression are diverse. One is “deep packet inspection” hardware, which allows authorities to track every unencrypted email sent, website visited and blog post published. When objectionable activities are detected, access to specific sites or services is blocked or redirected. And if all else fails, the entire Internet can be slowed for target users or communities.

In other cases, like in Ukraine, sites are taken offline with distributed-denial-of-service attacks, which overwhelm a server with digital requests, or else the routing system of the national Internet system is tampered with to make entire sites mysteriously unreachable. Entire categories of content can be blocked or degraded en masse; in Iran, we hear that all encrypted connections are periodically severed and reset automatically.