A coincidence is an occurrence where two or more events happen at the same time or in a way that seems related, but are actually unrelated. For example, you might think of a friend and then unexpectedly run into them later that day. These events can feel surprising or meaningful, even though they are simply the result of chance. Coincidences can happen in everyday life, such as finding a book you were just talking about in a store. They can also occur in larger contexts, like historical events or scientific discoveries, where unrelated factors align in unexpected ways, leading to surprising outcomes.