ATMEGA328P-PU Microchip 8-Bit MCU (DIP-28)

This is the DIP-28 sibling of the TQFP-32 ATMEGA328P-AU also in the catalog, the same genuine Microchip microcontroller but in the through-hole package that plugs straight into a breadboard or an IC socket, exactly the way an Arduino Uno's own socketed chip works. That socket-friendly form factor makes it easy to program a chip once and then move it between a breadboard prototype and a finished project, or swap in a freshly programmed replacement without any surface-mount soldering.