Websites are files on a computer. When you view a website, you are asking the computer to send you the files, then your browser shows them to you. 70% of the websites you see use PHP to make them interactive. So you can send things to the website too and it can respond. E.g. filling in a comment box and hitting 'post' adds the comment as a row to a spreadsheet. PHP has a flaw in its code that allows anyone to gain control of the computer that has the website on it. The organisation that provides PHP announced the vulnerability before a patch was available, meaning we're in a window where everyone knows about it (including baddies) but the good guys don't have an official solution. Some are just turning off their websites and waiting for the solution. Others are trying to fix it themselves. General chaos and lots of stressed techies across literally the entire planet because this affects the entire internet.