Sometimes called stylistic editing, this service involves a line-by-line edit focused on improving writing style, clarity, and conciseness. Where copy editing focuses on technical aspects of the text, line editing concerns itself with the flow and readability. Example of a line edit:

Original: The study uncovered that one in two chickens would peck enthusiastically at researchers who were wearing hats that had been strategically covered in corn.

Edit: The study found that 50% of chickens pecked at researchers who wore hats covered in corn.