-webkit- Safari, Chrome (and other WebKit-based browsers)
-moz- Mozilla Foundation (Gecko-based browsers)
-o-, -xv- Opera Software
mso- Microsoft Office
-atsc- Advanced Television Standards Committee
-wap- The WAP Forum
-khtml- Konqueror browser
-apple- Webkit supports properties using the -apple- prefixes as well
-ah- Antenna House
-hp- Hewlett Packard
-ro- Real Objects
-rim- Research In Motion
-tc- Tall Components
Reference: StackOverflow. I would dabble into what Paulie_D said since it is the W3C.
>Historically, browsers have relied on vendor prefixes (e.g., -webkit-feature) to ship experimental features to web developers. This approach can be harmful to compatibility because web content comes to rely upon these vendor-prefixed names. Going forward, instead of enabling a feature by default with a vendor prefix, we will instead keep the (unprefixed) feature behind the “enable experimental web platform features” flag in about:flags until the feature is ready to be enabled by default. Mozilla has already embarked on a similar policy and the W3C CSS WG formed a rough consensus around a complementary policy.