Everything means all things, without exception. When you clean everything in your room, you don't just tidy your desk or make your bed: you handle every single item, from the clothes on the floor to the books on your shelf to the dust under your bed.

The word captures totality. If someone asks what you learned in school today and you say “everything,” you're (probably jokingly) claiming you learned every possible thing there was to learn. When a library burns down, people mourn because everything in it is lost: every book, every map, every photograph.

Everything works differently from its cousin anything. “Did you bring anything?” asks if you brought something, while “Did you bring everything?” asks if you brought all the items you were supposed to bring.

People sometimes use everything for emphasis or exaggeration. When your friend says “you have everything!” about your collection of trading cards, they don't literally mean you own every card ever printed. They mean your collection is impressively complete. When something goes wrong and someone groans “everything's going wrong today,” they're expressing frustration, not claiming that literally all things everywhere are malfunctioning.

The phrase everything but the kitchen sink describes bringing far too many things, almost everything you can think of.