The short answer is that Internet Explorer is an outdated browser that negatively impacts user experience and has major security deficiencies. We recommend encouraging IE users to download a free, modern browser like Google Chrome of Firefox and discontinue using Internet Explorer immediately.
The longer answer is that Internet Explorer is an antiquated browser that has not been updated to be compliant with modern standards for the greater part of a decade. Building websites to be compliant with IE requires either a significant degredation of the quality of the site available to website visitors using a modern browser or a significant investment of time create alternate versions that are compliant with Internet Explorer.
Anyone currently using Internet Explorer has a degraded or ineffective experience on most any website. Given the poor browsing experience and security concerns the best course of action is to encourage users to change browsers.
Microsoft officially ends all support for IE in June of 2022.