A cleft sentence divides a message between two clauses to focus attention on one part. Compare Nia found the keys under the bench with It was under the bench that Nia found the keys. The cleft makes the location the focus.
It-clefts
An it-cleft uses it, a form of be, and the part you want to emphasize. In It was Nia who found the keys, the who clause gives the background, and Nia answers who found them. The initial it is a grammatical placeholder. See expletives for other placeholder uses.
What-clefts
A what-cleft can put the focus after be. In What Nia found under the bench was the spare key, the what clause sets up the thing she found. The spare key identifies it. Choose a cleft when the sentence needs to highlight or correct a specific detail. See emphasis for other ways to direct a reader’s attention.
