I am working through the Jest React tutorial for testing React components. The tutorial creates a Link React component; I'm unclear on the file extension of the file it is written in : 

[![enter image description here](https://i.stack.imgur.com/wrdzH.png)](https://i.stack.imgur.com/wrdzH.png)

How does the .react file extension work? Is it comparable to .jsx, or someway to namespace files that I'm not aware of?