Why is delta 0.5 at-the-money?

Could you please explain why the delta value of an at-the-money option is 0.5? I understand that delta measures the sensitivity of an option's price to changes in the underlying asset's price, but I'm curious about the specific reasoning behind this particular value for at-the-money options. Does it have to do with the strike price being equal to the current market price of the underlying asset? Could you elaborate on this concept further?