A paywall is the part of a website that stops you unless you pay. Some news sites let you read a few articles for free, then the paywall appears and asks you to subscribe. It is a newish internet word, informal enough for everyday talk about the web, but people also use it in serious news. The picture in the word is a wall you cannot pass without paying. It was built to sound like firewall — a wall that blocks something — only this wall blocks readers, not computer attacks. Though actually, people also use it as a verb: a paper may paywall its stories, meaning it puts them behind that wall. Not every “please log in” screen is a paywall; if they only want an account and no money, that is not quite the same.