How do I properly tag my images?

How do I properly tag my images? I used to be able to edit them a while back. Was that disabled because of abuse. Could tags also be pulled from the image meta data? Anything that has the weight increased should definately be considered as a tag. Again someone could even abuse that, but its much more work and only the person posting it could do it, but at least it would get my images tagged closer to what they are.

Right now only by clicking on the image itself, clicking the (i) button on bottom and add tags from there. I wonder why they removed that feature too.