The impact of computers increased dramatically when they were connected together to form the internet. Millions of users around the world log on to the web every day, forming part of a network that has revolutionised how people communicate, live, work and shop – yet few people could actually explain the inner workings of the system. Just how does information make its way across the web, through hundreds of computers to the right destination? How does a search engine find the desired page amongst billions of possibilities in a fraction of a second? What will the web be like in years to come? And are credit card numbers safe when they are sent out into the ether? In this lecture, Chris Bishop untangles some of the mysteries of the web. He reveals one of the most surprising results in computer science, and shows how it is used to make web pages secure. He also studies the different ways of scrambling information to stop eavesdroppers from reading it, and explains how quantum physics can provide a secret means of transmitting data over the internet. The future of the web remains a hotly debated topic. Experts predict a range of innovations, including an increase in the number of mobile devices that can access the web. Yet questions of web security, privacy, government regulation and the impact on social interactions as people spend more time online remain areas of great speculation. It is clear that the internet will be a major part of the future – but that future is still to be shaped.