Taking advantage of strong disagreements inside Germany, the Italian feudatories rebelled and, in 1002, elected Arduino, Marquess of Ivrea, king of Italy. He distinguished himself particularly because of his fights against the Bishop of Ivrea.

Today, Arduino distinguishes itself in price, capability, openness, and ease of use - but first things first.
Arduino is an open-source computing platform based on a simple board, and a development environment for writing software. The Arduino board hosts an Atmel MicroController chip, the AVR-ATMega8, which has 8-KByte self-programming Flash Program Memory, 1-KByte SRAM, 512 Byte EEPROM, 23 I/O pins, 6 or 8 Channel 10-bit A/D-converter, and 16 MIPS throughput at 16 MHz.
The other IC on the board is an FTDI FT232RL, a single chip USB/Asynchronous serial data transfer solution, with 256 Byte receive and 128 Byte transmit buffer.

Considering that these two chips alone would cost you about $10, the $32 that Spark Fun charges for the fully assembled, RoHS compliant, and tested Arduino board looks like a real bargin.
Moreover, like Tod points out, the Arduino looks even more attractive, when compared to the $119 Basic Stamp, which is another embedded computing platform, mainly for hobbyists and education.
However, Arduino is actually two things, ...