The term “performance art” comes as a loaded and convoluted one these days, something as confusing as it is fascinating. In its foundations, performance art refers to an artwork dependent on the presence of the artist hisself or herself, rather than an artifact made by him or her. But there’s also something outside of what conventional notions of theater or other performance imply. There’s a sense of the artist’s autonomy in composition and endurance in performance, the work’s social critique, the difficulty to replicate the action in presence and effect—these are the markers of a great work of performance art. We’ve collected The 25 Best Performance Art Pieces of All Time here—some are vaguely not safe for work.