To unzip means to open something by pulling apart a zipper, the metal or plastic fastener with interlocking teeth that you slide together or apart. You might unzip your jacket when you walk into a warm building, or unzip your backpack to grab your lunch. The zipper was invented in the early 1900s and quickly replaced buttons on many items because it’s faster and more secure.

In the world of computers, unzip has a second meaning: to decompress or expand a file that was compressed to take up less storage space. When you download a zipped file (also called a zip file), it’s like getting a tightly packed suitcase. You need to unzip it to access all the individual files inside. This kind of zipping doesn’t involve actual zippers, of course. The computer term borrowed the word because compressing files feels like closing a zipper: you’re squeezing things together to make them smaller and more manageable.

Both meanings share the same idea: opening something that was closed or packed together, whether that’s a coat or a collection of computer files.