ActiveX

Some convoluted proprietary solution Microsoft came up with because they thought web standards meant being compatible with Internet Explorer 6.

A case study on why platform-specific proprietary solutions are bad for the web: Korea.
ActiveX was the reason why the Korean web was stuck in the early 2000's for over a decade. Everyone there was using it for either adding multimedia and/or security encryption, and this resulted in the country being one of the last nations to still hold onto IE 6 during the second browser wars.

This made it impossible to do any online banking, shopping, social media (Cyworld was big back then), etc., so using Firefox or Chrome meant you're SOL if you live in Korea.

Some native English teacher in Korea - Hey Soyoung, why can't I use my Mac to log into Nonghyub Bank?
Soyoung - Oh, you have to use Internet Explorer 6 and enable ActiveX. Korea uses advanced software for their websites?
English Teacher - ActiveX? You mean that P.O.S. Microsoft abandoned years ago? Wtf...