A bid adjustment is when you tell Google to spend more or less money on your ads depending on certain conditions, like the time of day, the device someone is using, or their location. For example, if your data shows that mobile users barely buy from you, you can lower your bids for mobile so you spend less showing ads to them. If evening hours bring the most sales, you raise bids for that time. It is a way to control where your money goes. How do you currently manage your bid adjustments?