ごちそうさまでした (Gochisōsama deshita) means "Thank you for the meal." You say this after finishing a meal, expressing gratitude to the person who prepared or paid for it, or simply acknowledging the food itself. It's an essential mealtime courtesy.

食事を終えた時に、料理を作ってくれた人やご馳走してくれた人への感謝を伝える言葉です。