Since I don't know what "these" refers to here, I will just assume that the question addresses social networks generally.
Some impacts are:
Positive
-better information
-security (you can mark people safe during Earthquake)
-faster contact with peopl
-possibility of forming groups
-additional communication platform
Negative:
-less privacy
-lack of control over data
-being able to spy on people
-being able to find things from the past
-bosses spying on their workers
