You can’t trust the reader without trusting yourself. Writing works best when you are conﬁdent about what you write.
When in doubt, assume the reader knows nothing. But never assume that the reader is stupid. In other words, don’t overestimate what the reader knows and underestimate what the reader understands.
She may not know it herself, but your reader will want the answers to three questions:
What is happening?
So don’t disappoint her. Deliver the goods.