Raspberry Pi is known for making really tiny computers, with the company’s flagship line of products about the size of a deck of cards. The Raspberry Pi Zero line is even smaller, since these little 2.6″ x 1.2″ x 0.2″ drop most of the ports found on larger models.
The Pi Zero does still have a a built-in processor, memory, micro USB ports, a mini HDMI port, and a microSD card reader for storage. And there’s a 40-pin header that you can use to connect hardware that’s compatible with Raspberry Pi’s GPIO setup. There’s just one catch: you need to actually solder pins to the board if you want to use those headers, because they’re left empty by default on the $5 Razpberry Pi Zero and $10 Raspberry Pi Zero W (the one with WiFi and Bluetooth).
Or you can buy a new model, called the Raspberry Pi Zero WH. It has the GPIO pins pre-soldered.
The new Raspberry Pi Zero WH sells for about $15, and the only thing that really makes it different from the Raspberry Pi Zero is that no soldering is required to use those GPIO pins.
Both models feature 1 GHZ Broadcom BCM2835 processors, 512MB of RAM, 802.11b/g/n WiFi, Bluetooth 4.1, a micro SD card slot, a mini HDMI port, and two micro USB ports (one for power, and one for data).