In general, it is not recommended to support Internet Explorer anymore. The cost of maintaining compatibility exceeds the benefits in many cases. Usage of Internet Explorer has dropped sharply over the last years and nowadays the percentage of website visitors that still use Internet Explorer on your website is likely very low.
Making a website work with Internet Explorer is costly. Internet Explorer lacks support for many website features and best practise web development approaches. In order to make a modern website compatible with Internet Explorer, workarounds and fixes specific to Internet Explorer have to be implemented. This requires extra efforts.
Here you can see the usage statistics for Switzerland (as of 2021). Internet Explorer is used by a mere 3% of website visitors on average, while Chrome, Firefox and Safari together cover 85% of all website visits.

Interesting fact: Even Microsoft themselves have become tired of Internet Explorer and have made moves to stop supporting the outdated software, for example in this blog post in August 2020.
👉 At what. we include Internet Explorer 11 compatibility in our offers as an optional item. This serves as an information for the client that by default the website wont be optimized for Internet Explorer.
What browsers should websites be optimized for in 2021?
At what. we have established the following compatibility policy:
The software is optimized for the following devices and browsers: - Chrome (Windows, Mac OS X, Android, iOS) - Safari (Mac OS X, iOS) - Firefox (Mac OS X, Windows) - Microsoft Edge (Windows). Mobile Devices: - Latest Google Phone (Standard Version) with the latest Android OS - latest iPhone (Standard Version) with the latest iOS. The testing takes place on browserstack.com with the latest available operating system for a specific browser.