Those square holes on USB-A connectors serve an important purpose.
USB-C ports might be the de facto port today when it comes to charging and data transfer, but that wasn't always the case. Before consumers got the current reversible design, the original Universal Serial Bus, or USB, was designed in the late '90s by Intel, Microsoft, NEC (Nippon Electric Company), IBM, Compaq, DEC (Digital Equipment Corporation) and Nortel.
The USB Type-A connector was designed to simplify the task of interfacing with plug-and-play peripherals like keyboards and printers. Broad compatibility meant that users could minimize their cable collection and rely on a standard port for convenience. Over the years, new standards like USB 4 brought dramatic improvements in power delivery and data transfer speeds.
Most male USB-A connectors have two square-shaped holes. People rarely think about this design feature when they plug in everything from cables to storage devices, but there's more to them than mere aesthetic value. Put simply, they ensure the connector stays plugged in. Here's how this engineering decision plays into consumer technology's once-ubiquitous standard.
Peer into a female USB-A port and you'll spot spring-loaded retention clips meant to snap into the male connector. The square holes are a part of this locking mechanism, ensuring a secure connection.
