You won’t go very far in your journey to learn about creative writing without coming across the advice - or it might even be the exhortation - to show, don’t tell.
It’s very important to show rather than tell because showing involves the reader in the story and engages her. It even - as I explain below - makes her a co-creator in the story, and she has an ownership - unconscious, but real - of the story and hence more of a commitment to it. And as I often say, the ultimate objective is to keep the reader reading - and showing is a powerful tool to do this.
Telling on the other hand, divorces the reader from the action. It distances her.
How does all this work?
Telling is handing the reader the information pre-digested in a way. You are telling the reader what conclusion to come to.
Alternatively, showing is describing exactly what is happening, and letting the reader reach her own conclusions.
An example might make this clear.
Sarah told James, “I’m going to Paris tonight.”
“What?” he demanded, angry at that news. He strode towards her. “Don’t do it.”
It’s pretty flat and unengaging, isn’t it?
Compare it with this:
His eyes narrowed and his nostrils flared. He strode towards her, and said, his lips tight and pale, “Don’t do it.”
Do you see how you - the reader in this case - immediately know that James is angry, without even being told? You’re given the information, and you come to the conclusion that he’s angry. It’s much easier to visualise the scene, and because of that that, you’re much more involved in the story.
Also, as mentioned above, by absorbing the evidence as presented, and coming to the conclusion, in a way the reader is co-writing the story, and is hence more involved and committed, which is what you - as the writer - want.
It’s much harder work to show rather than telling, of course. You, as the writer, have to be able to visualise clearly what’s going on in order to describe it. I often act scenes out. I’ll stand in front of a mirror and deliberately make myself feel different emotions, and see what happens to my expression, and then write that.
Do I feel silly? For sure! But if it was easy, sure everybody'd be doing it. And it really does work.