"Horizontal Lines" exemplifies LeWitt's conceptual approach to art, where the idea or system behind the work takes precedence over its visual execution. The work typically consists of evenly spaced horizontal lines drawn according to predetermined instructions, reflecting LeWitt's interest in algorithmic processes and the dematerialization of the art object. Like much of his practice, the piece can be executed by assistants following the artist's written guidelines, emphasizing that the concept is the artwork rather than any single physical manifestation.