Raspberry Pi is credit card sized single-board computers developed by Raspberry Pi Foundation, UK. All models (Pi A, A+, B and B+) feature a system on a chip (SOC) that includes an ARM-compatible processing unit (700 MHz to 1.2 GHz) with on-chip graphic processing unit and on-board memory (256 MB to 1 GB RAM). RPi boards have USB slots, HDMI besides video and audio output. Lower-level output is provided by a number of general-purpose input/output (GPIO) pins.

SD cards are used to store the operating system and program memory in either the SDHC or MicroSDHC sizes. The Foundation provides Raspbian OS (a Debian-based Linux distribution) as well as Ubuntu and windows 10 IoT Core.

check more on Raspberry-pi projects towards IoT:

Getting started with the Internet of Things