why github claim it is distributed version control system ?

Question

just follow this link https://en.wikipedia.org/wiki/GitHub

 

they are saying " It offers all of the distributed version control and source code management "

 

what they try to mean distributed version control ?

 

if we upload a project to github then many people around the world can work on the same project.......that is why GitHub is called distributed version control ?

 

if yes then online TFS is also provide same functionality. if we upload a project to TFS then many people around the world can work on the same project but TFS never claim that it is distributed version control.

 

so please some one who understand distributed version control then please explian why GitHub is consider distributed version control.

 

thanks