The answer to the riddle "What stays in a corner and travels around the world?" is a stamp. Stamps are typically placed in the corner of an envelope and, when the envelope is mailed, that stamp helps facilitate the envelope's journey around the globe.
This riddle plays on the dual meanings of "corner" and "traveling," cleverly combining the physical location of the stamp on a letter with its role in sending mail worldwide. It's a light-hearted way to highlight how something small can have a significant impact in connecting people across distances. If you're interested in more riddles or similar word play, feel free to ask!