What is PHP and why did it spark a global cyber-security scramble?

–BBC News 

What is PHP and why did it spark a global cyber-security scramble? For more than a decade, serious flaws had gone undetected in technology underpinning much of the internet. It took artificial intelligence (AI) to bring them to light and caused a global cyber-security alert. The vulnerabilities lie within a programming language called PHP, which has been used internationally since the 2000s to build websites. Governments and cyber-security agencies around the world scrambled to contain the fallout of this discovery on Wednesday, and have urged website operators to install a new emergency fix or consider taking their platforms offline.