Self-reference is when something refers to itself. For example, a book that talks about its own story or a painting that depicts itself is using self-reference. This concept can be found in literature, art, and even in everyday conversations, where someone might say, "This sentence is true." It creates a unique loop of meaning that can be both intriguing and complex. In mathematics and logic, self-reference can lead to interesting paradoxes. A famous example is Russell's Paradox, which questions whether a set that contains all sets that do not contain themselves includes itself. Such self-referential statements challenge our understanding and can reveal deeper truths about language and reasoning.