Why MathML 3?

MathML 2 was first adopted in 2001. Experience with MathML has accumulated over the years and the web environment has changed somewhat since then. Released in 2010 and updated in 2014, MathML 3 includes several requested features and some changes to update the recommendation to the current and emerging standards. MathML 3 also contains lots of smaller changes to clarify the spec and unify attribute values so that compatibility between implementations is more likely. With the exception of a few very minor changes for features not widely implemented, MathML 3 is backward compatible with MathML 2.

The big changes are:

Some of the smaller changes are: