Leaving a microwave plugged in does consume a small amount of electricity, even when it's not in use. Like many electrical appliances, microwaves often have a standby mode that keeps certain functions active, such as displaying the time or listening for signals from a remote control. This standby power usage is sometimes referred to as "vampire power" or "phantom load."
While the amount of electricity consumed by a microwave in standby mode is generally minimal, it can still contribute to your overall energy consumption over time. If you're concerned about energy efficiency and want to minimize standby power usage, you can consider using a power strip with an on/off switch or simply unplugging the microwave when it's not in use. This way, you can completely cut off power to the appliance and eliminate any standby power consumption.