Some time ago I lost track of the versions of Internet Explorer that were appearing, on the one hand because my main operating system has been Linux for years and on the other hand whenever I had to install a new Windows I would update IE but as the main browser I would leave Firefox or Chrome.
Yesterday, all versions prior to Internet Explorer 11 stopped receiving support, that is, Internet Explorer 8, 9 and 10, which are versions that are still used, will no longer receive security patches that fix the vulnerabilities that appear.
The 11 is the latest version and can be used in Windows 7, 8.1 and 10. In this latest operating system you can also use Microsoft Edge which is the browser that comes integrated.
In Windows Vista SP2 version 9 will continue to receive updates as you can see in the table published here, this happens because it is the latest version of IE that the operating system supports.
The best way to avoid messing around with versions is to install the latest Windows Update offers in its automatic updates, IE 11 can also be downloaded manually from here.
On the other hand, the Windows 8 operating system also stopped receiving support, its users must update to version 8.1 or 10 if they want to be safe on the internet.
Updating browsers and their add-ons is important as a vulnerable browser can be easily attacked and the gateway for malware. You could end up being infected even automatically when visiting a manipulated website (see example video).