The definition of an idiom is a phrase that conveys a different meaning than what's found on the surface. Like how when you say you and your friend are like two peas in a pod, you're not literal peas. You're just saying that's how close you are.
1.someone who can understand why media was created
2.someone who can analyze different forms of media
3.someone who can evaluate the effectiveness of media
Global warming and changing climates there you go my friend