So can the wifi admin see what pictures or what I search in apps like Instagram, Twitter, Vine. Here's an example- I search fight videos on Instagram and I end up watching an Instagram video, can my wifi admin see that?
91 Answer
The answer is "It depends".
If you are going to unencrypted sites, it is possible for anyone in the middle - including whoever it is that controls your WIFI connection - to see the traffic going in both directions. They can see pretty much anything set "unencrypted"
In the "normal case" of going to secure (https) sites, the WIFI administrator would not be able to see exactly what you are doing. They would be able to get a sense of it from hints - including DNS queries - which would give an indication of which services you were using - but they would not be able to see the actual content (ie what images or videos you were looking at). They could get some vague idea what you were doing by looking at the volume of information being transferred, and the timing of data packets.
In the "special case", if the WIFI provider has put a root cert on your computer or is otherwise forcing you to use a proxy they can see exactly what you are doing - as if it was unencrypted. In most cases they can't practically do this - unless its a corporate environment - as they need access to the software running on your computer.
