The battery symbol seen beside many USB ports is not just decorative. It usually identifies a USB Power Delivery (PD) port, which supports higher power output and a more sophisticated charging protocol. Through a digital handshake, the port and charger negotiate the correct voltage and current, reducing the risk of overheating while enabling faster charging for devices like laptops.
USB PD was introduced in 2012 and updated in 2021, allowing up to 240W of power. That makes it capable of supporting demanding hardware such as high-end laptops and monitors. The port also supports bidirectional charging, so a laptop can charge a smartphone or earbuds, and some models allow this even when the laptop is asleep or shut down. The trade-off is that leaving a device plugged in can drain the laptop's battery, though many manufacturers include a way to disable the feature.
There is no universally consistent icon for USB PD. The USB Implementers Forum defines an official symbol—a battery shape made with negative space—but companies often use their own battery logos, a lightning bolt, or the letters "PD." Some devices, such as Apple's Thunderbolt ports, support USB PD without any visible marking. When in doubt, the source recommends checking the manufacturer's specifications or user manual.