There is an official website with all the relevant information.
Here is a beautiful drawing by Rafael Malmagro (ESO Year 2) to illustrate this importante day for languages.
Having a universal language like English can be great on many occasions but there is a downside: other languages are quickly disappearing.
In the last years there have been several movements to preserve these "endangered" languages around the globe. Here are a few examples:
* The Rosetta Project is a global collaboration of language specialists and native speakers working to build a publicly accessible digital library of human languages.
* The Endangered Languages Project tries to support language documentation and preservation around the world.
Endangered Languages Project

Endangered Languages Project
A project to support language preservation and documentation around the world