Total credit for this concise, concrete explanation of "social media" goes to a handout I received from TRTA (Texas Retired Teachers Association).
"I'm eating a donut."
"I like donuts."
"This is where I each donuts."
"Here's a video of me eating a donut."
"Here's a vintage photo of my donut."
"Here's a pretty donut recipe."
"My skills include donut eating."
"Now listening to "Donuts."