Micro-USB vs. USB-A

Micro-USB (Micro-B) was the dominant charging and data connector on non-Apple smartphones and small electronics from the late 2000s through the mid-2010s. Its USB 3.0 variant added a second, wider tab beside the standard 5-pin plug for extra SuperSpeed pins -- a design most phone makers skipped, keeping plain USB 2.0 Micro-B nearly universal in practice.

USB-A (Standard-A) is the flat rectangular connector on host ports -- computers, chargers, hubs. It used 4 pins for USB 1.x/2.0 speeds; a 9-pin variant, adding 5 SuperSpeed contacts, extended it to USB 3.0+ in 2008 without changing the external shape or requiring a new socket design.