Uploading is described as transferring a file(s) like photo, audio file etc. to a server on the web. I wonder a couple of things how uploading occurs as network/communication means. For example, when I upload a photo from my computer to my facebook profile, does it also mean downloading that file because I display it on my web browser(client) too ?
Second question, uploading is the reverse process of the downloading. However, once we upload a file to a server, we don't have to make port forwarding. On the other hand, if downloading is sending requests to a server from a private network(accessing the outside), by this means, uploading should be accessing the private network from outside. That way, port forwarding should be performed. But even we don't do it, transferring is working. How ?