To set up something means to arrange, assemble, or prepare it so it's ready to use. When you set up a board game, you place all the pieces in their starting positions. When teachers set up a science experiment, they gather materials and arrange equipment before the class begins. Setting up a tent means putting all its parts together so you have shelter for the night.

The phrase can also mean to create or establish something new. A business owner might set up a new company, or a school might set up a tutoring program. When you set up a meeting with friends, you're arranging the time and place where everyone will gather.

Sometimes set up describes preparing conditions that lead to something else. A chess player might set up a clever trap by positioning pieces where an opponent won't notice the danger. In stories, an author sets up surprises by including small clues early on that become important later.

There's also a less common meaning where someone gets set up, meaning they were tricked or falsely blamed. If a character in a mystery novel was set up for a crime they didn't commit, someone planted false evidence to make them look guilty. But in everyday conversation, you'll hear set up most often when people are simply getting things ready: setting up chairs for an assembly, setting up a new phone, or setting up dominoes to knock them down.