Those big ugly power supply bricks that we all carry around for our laptops... it converts AC power to DC power that's used by your device. Your cell phone adapter, your Xbox/PS5, etc..etc.. Nearly every one of our electronic devices require converting AC input to DC so you can plug into a standard wall outlet.
You can expect about a 5-20% on average power loss just to do the conversion. With alternative energies coming online from DC sources, the power loss is starting to get pretty bad.
DC Input (solar/wind) -> High-Voltage AC (for transmission lines) -> Low-Voltage AC (240v coming into your home) -> Power Brick -> DC Output (just so you can charge your phone).
5-20% power loss each time that's converted just to pull 5 volts @ 3 amps just to charge a cell phone.