Arduino is an open-source platform used for building electronics projects. Arduino consists of both a physical programmable circuit board and a piece of software, or IDE that runs on your computer, used to write and upload computer code to the physical board.

With the Arduino, you can design and build devices that can interact with its surroundings. The Arduino boards are basically a tool for controlling electronics. They are able to read inputs with their onboard microcontroller (eg. Light on a sensor, an object near a sensor) and turn it into an output (Drive a motor, ring an alarm, turning on an LED, display information on an LCD).

The Arduino platform has become quite popular with people just starting out with electronics, and for good reason. Unlike most previous programmable circuit boards, the Arduino does not need a separate piece of hardware (called a programmer) in order to load new code onto the board  you can simply use a USB cable. Additionally, the Arduino IDE uses a simplified version of C++, making it easier to learn to program.

A typical example of the Arduino board is Arduino Uno. It includes an ATmega328 microcontroller and it has 28-pins

Why Arduino?

Arduino has been used in thousands of different projects and applications. The Arduino software is easy-to-use for beginners, yet flexible enough for advanced users. It runs on Mac, Windows, and Linux. Teachers and students use it to build low cost scientific instruments, to prove chemistry and physics principles, or to get started with programming and robotics.

There are many other microcontrollers and microcontroller platforms available for physical computing.But  Arduino simplifies the process of working with microcontrollers, it provides some advantage for the users and interested amateurs over other systems.

Advantage

Inexpensive - Arduino boards are relatively inexpensive compared to other microcontroller platforms.

Cross-platform - The Arduino Software (IDE) runs on Windows, Macintosh OSX, and Linux operating systems. Most microcontroller systems are limited to Windows.

Simple, clear programming environment - The Arduino Software (IDE) is easy-to-use for beginners, yet flexible enough for advanced users to take advantage of as well. For teachers, it's conveniently based on the Processing programming environment, so students learning to program in that environment will be familiar with how the Arduino IDE works.

Open source and extensible software - The Arduino software is published as open source tools, available for extension by experienced programmers. The language can be expanded through C++ libraries, and people wanting to understand the technical details can make the leap from Arduino to the AVR C programming language on which it's based. Similarly, you can add AVR-C code directly into your Arduino programs if you want to.

Open source and extensible hardware - The plans of the Arduino boards are published under a Creative Commons license, so experienced circuit designers can make their own version of the module, extending it and improving it. Even relatively inexperienced users can build the breadboard version of the module in order to understand how it works and save money.

 Types of arduino

Arduino makes several different boards, each with different capabilities. In addition, part of being open source hardware means that others can modify and produce derivatives of Arduino boards that provide even more form factors and functionality. If you’re not sure which one is right for your project, check this guide for some helpful hints. Here are a few options that are well-suited to someone new to the world of Arduino:

Arduino Uno (R3)

The Uno is a great choice for your first Arduino. It's got everything you need to get started. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a USB connection, a power jack, a reset button and more. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

Arduino Due

The Arduino Due is a microcontroller board based Original Arduino Due Board on the Atmel SAM3X8E ARM Cortex-M3 CPU. It is the first Arduino board based on a 32-bit ARM core microcontroller. It has 54 digital input/output pins (of which 12 can be used as PWM outputs), 12 analog inputs, 4 UARTs (hardware serial ports), a 84 MHz clock, an USB OTG capable connection, 2 DAC (digital to analog), 2 TWI, a power jack, an SPI header, a JTAG header, a reset button and an erase button.

LilyPad Arduino

The LilyPad consists of an ATmega328 compatible with the Arduino bootloader and a minimum number of external components to keep it as small (and as simple) as possible.This board will run from 2V to 5V and offers large pin-out holes that make it easy to sew and connect. Each of these pins, with the exception of (+) and (-), can control an attached input or output device (like a light, motor, or switch).

Arduino Mega (R3)

The Arduino Mega is like the UNO's big brother. It has lots (54!) of digital input/output pins (14 can be used as PWM outputs), 16 analog inputs, a USB connection, a power jack, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. The large number of pins make this board very handy for projects that require a bunch of digital inputs or outputs (like lots of LEDs or buttons).

Arduino Leonardo

The Leonardo is Arduino's first development board to use one microcontroller with built-in USB. This means that it can be cheaper and simpler. Also, because the board is handling USB directly, code libraries are available which allow the board to emulate a computer keyboard, mouse, and more!

Arduino Architecture

Basically, the processor of the Arduino board uses the Harvard architecture where the program code and program data have separate memory. It consists of two memories such as program memory and data memory. Wherein the data is stored in data memory and the code is stored in the flash program memory. The Atmega328 microcontroller has 32kb of flash memory, 2kb of SRAM  1kb of EPROM and operates with a 16MHz clock speed.

Arduino Software

After knowing the hardware of Arduino, you will require software and programming to make your Arduino come to life and allow it to interact with various sensors and shields. To program your Arduino, you will require the Arduino IDE software. 

About Arduino IDE

1. Arduino IDE makes it easy for you to write code and upload it on your Arduino board.
2. This program is cross-platform which means it is able to run on Windows, Mac OS X, and Linux compared to other microcontroller systems which can only run Windows.
3. This software can be used with any Arduino board like Arduino UNO, Arduino Mega (R3) etc.
4. The environment is written in Java and based on processing and other open-source software.
5. This program uses a simplified version of C++ with syntax highlighting and other features which makes it easier to learn to program which is perfect for beginners to learn programming and coding!
6. After you finish writing your code, you can then easily load your code on your Arduino IDE with a USB cable with a click of a button.

Applications of Arduino Technology

1. The Obstacle Avoidance Robot Operated with Arduino

2. Arduino based Home Automation

3. Arduino based Controlling of Electrical Appliances using IR

4.Underground Cable Fault Recognition using the Arduino Board

Go Here for Boards Compatible With Arduino

This guide has been written in reference to sparkfun.com