In our computing lessons, we are learning about internet communication. We have learnt that a search engine makes an index using a program called a ‘web crawler’. This automatically browses the web and stores information about the pages it visits.  Every time a web crawler visits a webpage, it makes a copy of it and adds its URL to an index. Once this is done, the web crawler follows all the links on the page, repeating the process of copying, indexing and then following the links. It keeps doing this, building up a huge index of many webpages as it goes.