what is the small arrow on top of the network status bar?

[aliencatos]

hi

since windows 8.1 I believe, I see some time a small arrow on top of my network status bar



i don't know what it mean ??

​THX

 

[GabrielStorm]

it designates data being passed to the network.

 

[VaderJr]

Any idea what data would this be since I cannot browse anything on mobile data when this icon comes up.