Windows XP is the record holder as the longest-lived Microsoft OS. After today, Microsoft will stop serving the general public any security patches for vulnerabilities in XP. The lack of patches for XP will increase the likelihood of a malware infection by at least two-thirds. Windows XP Professional, the business class version of the OS, had already been awarded a retirement date of April 2014. Microsoft will continue patching Windows XP, but that you have to pay for the next 12 months of patches.”]
Source: https://www.csoonline.com/article/2141022/faq-good-bye-old-pal-old-paint-windows-xp.html