Backup means having something ready in case your first choice doesn't work out. When a soccer team brings backup players to a game, they're prepared if someone gets injured or tired. When you save a backup copy of an important school project on a second flash drive, you're protecting yourself in case the first one gets lost or stops working.

The word can be a noun or a verb. As a noun, a backup is the thing you keep ready: “I always keep a backup pencil in my bag.” As a verb, to back up means creating that safety net: “Make sure to back up your files before the computer update.”

In technology, backup is crucial. When you back up photos from your phone to a computer, you're creating copies so you won't lose precious memories if your phone breaks. Companies back up their data every night because losing customer information or financial records could destroy their business.

People can be backups too. If your best friend can't make it to the movie, having a backup plan means you've already thought of someone else to invite or something else to do. Backup singers support the main vocalist. Backup generators kick in when the power goes out.

Smart planning includes backup: the spare tire in a car, the understudy in a play, the reserve parachute a skydiver wears. Having backup doesn't mean expecting failure; it means being prepared for real life.