What an Arduino is and what it can be used for?

It is a printed circuit board built around a controller chip. The chip itself can be programmed depending on what we want to use it to. The big think is that one does not require advance programming skills, it is easy to learn the commans. One can find a lot of help on the internet. The chip can be programmed from a computer through the USB cable. The board has a led and more analog in and output connectors.

What can it be used for? Your fantasy is the limit. I used it for the following so far:

-flashing the led programatically
-measuring temperature
-measuring voltage
-battery capacity measurement

It sends the measured data immideately to the computer on the USB cable, or it can save the data in its memory. If we connect an LCD screen to it, then it can show the data itself. It can be run on battery or from the power from the USB cable or from a power supply.

Of course different projects require different other stuff to be bought. For instance the sensors which data we want to use. One could control a relay depending on the data from the sensors, which for instance would control a lamp connected to the mains power. You can buy so called "shields" to it which expands its capabilities. Wifi shield, bluetooth shiled, SD card shield, sound module, lcd screen. You can connect RF modules to it, you can build an alarm system. You can buy a GPS shield or a GSM shield. These are only some examples.

I have bought mine on 2010.01.07. for 27,51 USD (today it would worth 29,89 USD counting inflation). It can be bought much cheaper today, you can find one for 3,5 USD including shipping from China.

Who have created this wonderful thing? The whole story can be found here. In short, an Italian joungster with his partners has created its prototype back in 2003. Its name was not Arduino back then but it was called "Wiring". Then later there are more threads in the story, who used who's invention, why he used it later, what company he founded. There were quarrels as well as we would imagine. The board was called "Arduino" from 2005. They say, that the name came from a bar where the creators were hanging by at that time. This may be an urban legend.

Anyone can build such a board, they have shared its schematics. Its website is: www.arduino.cc.