Historic tidbit: Mozilla had a slew of "internal" prefixes to be used in their UI and extensions, but Apple really broke new ground and made them mainstream when the iPhone came out and really needed CSS to be useful. That's when stuff like -webkit-transition` and the fabulous `-webkit-box-reflect` were pushed out without waiting for anyone.
-ms- wasn't really a thing until IE10 if I remember correctly, when they started prefixing their own IE5-era properties like the DirectX-based `filter` [citation needed]
-ms- wasn't really a thing until IE10 if I remember correctly, when they started prefixing their own IE5-era properties like the DirectX-based `filter` [citation needed]