Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It’s intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments.
Source: http://www.arduino.cc/

Microcontroller

Arduino is a microcontroller on a circuit board which makes it easy to receive inputs and drive outputs.

A microcontroller is a integrated computer on a chip.

Inputs

Some examples of inputs would be a temperature sensor, a motion sensor, a distance sensor, a switch and so forth.

Outputs

Some examples of outputs would be a light, a screen, a motor and so forth.

TL;DR

Arduino is a small computer that you can program to read and control electrical components connected to it.

Software download:-  :)

Arduino Software

Instalation:- :)

Unzip the file and install the soft ware.. Then open the software... and connect your arduino to your computer..,,

when it opens go to tools

 

 

 

 

 

 

Then goto board...

then chose Arduino genuni Uno...

then go to port...

choose your correct port... where your arduino is connected,in my case it is on port 3...

then go to file...

then Examples...

then go to basics then blink and then click on it...

then click on upload and wait till the Arduino upload its code to the microcontroler...

then you will notice the blinking of led on the Arduino Board...

Thanks....