What does 'back to square one' mean?

What it means: Having to start over from the beginning after a plan or attempt has failed.

"The deal fell through — we're back to square one."
"The prototype didn't work, so it's back to square one."

Where it comes from: Disputed. Possibly from early board games where landing on square one meant restarting. Another theory points to BBC radio football commentary in the 1930s, which divided the pitch into numbered squares on a printed grid.

What it implies: Effort has been wasted. You're not just behind — you're at the starting point with nothing to show for your progress so far. More absolute than "we've had a setback."

• "Start from scratch" — similar, implies no progress retained
• "We're starting over" — plain
• "We're back at the beginning" — direct

Tags: idioms, starting over, failure, business English