The writer's world is another way of saying; "The scene that is being set for the story to be told. Time, Location, Characters, Mood, Situation, etc.
For example, If you were telling a story about Dungeons and Dragons, perhaps you would mention that the main characters, Corlon, a Fighter and Esmerelda, a Sorceress are Trapped in a Dragon's Cave guarded by a Large one-eyed Cyclops and a Very Large Hungry Green Dragon. And so on.
Answer:
<u>It's</u> nice that <u>they're</u> friendly.
Explanation:
"It's" means "it is". "They're" means "they are".
It is nice that they are friendly.
A comma is just a pause that off-sets a phrase. A colon is used to indicate a major division in a sentence where a more distinct separation is felt between items
