Almost every Arduino and compatible variant uses a microcontroller containing an amount of EEPROM (electrically erasable programmable read only memory) which is non-volatile - in other words it remembers what has been stored within after the power is turned off. However using the normal Arduino EEPROM commands can be limiting for the beginner or those in a rush, as you can only store byte variables. Trying to store floats, larger integers and other types suddenly becomes bit more of a challenge.
However not anymore. Thanks to Thijs Elenbaas and his Extended EEPROM library, you can now store and retrieve int, long, float and double variables to the EEPROM with ease. This suddently increases the usefulness greatly, as logged data or precise settings can be stored quickly. Furthermore to preserve the life of the EEPROM (remember - it's finite) there's a command that only replaces a memory location with a variable if the contents are different. Very clever.
If you're new to Arduino and want to join the fun, the first step is a solid board for your projects - our Freetronics Eleven - the Arduino-Uno compatible with low-profile USB socket, onboard prototyping space and easy to view LEDs: