"Show, Don’t Tell"

There’s a simple reason that this is perhaps the most commonly used phrase where descriptive writing is
concerned (and that you may well have heard it plenty of times already): this is truly the fundamental
principle of descriptive writing. When it comes to describing something, ‘telling’ the reader about it comes
off as flat, vague, and not particularly memorable; ‘showing’ the reader the object -- describing it in such a
way as to paint it in words, and bring it to life in the reader’s eye -- renders the object far more vivid,
visible, and active.
But what exactly, are "telling" and "showing?"
Telling is another way of saying ‘summarizing.’ Here’s a writer ‘telling’ readers about a room:
"It was a nice room, a warm room. It was a happy place to be."
The reader reads this and says to her or himself, "okay, but why? What did the room look like? Why was it
a happy place to be? Was it warm, or hot? Or does the writer mean warm in terms of temperature? I can’t
really see or feel this room; I wish I’d been given more details." These two sentences may represent exactly
how the writer feels about the room, but to the reader they aren’t vivid enough to register this room as any
different from any other room. More importantly, the reader is unable to experience the qualities of this
room that the writer intends; because the reader has only been ‘told’ about the room (and told in very vague
terms), the room itself remains fuzzy and unclear (essentially invisible), and the qualities of niceness,
warmth, and happiness are merely the writer’s impressions of the room, nothing the reader can connect to.