Arduino IDE

Arduino IDE (Integrated Development Environment) is the open-source software Arduino.

It is a text editor like a notepad with different features.

It is used for writing code, compiling the code to check if any errors are there, and uploading the code to the Arduino.

It is a cross-platform software which is available for every Operating System like Windows, Linux, macOS. It supports C/C++ language.

Installing Arduino IDE

1. Go to https://www.arduino.cc/en/software
2. Download the appropriate version for your OS (Windows/Mac/Linux)
3. Install the software with default settings
4. Connect Arduino board via USB cable
5. Go to Tools > Board > Select 'Arduino Uno'
6. Go to Tools > Port > Select the COM port

IDE Interface 

Structure of an Arduino Sketch

Every Arduino sketch has two mandatory functions:

void setup() {

  // Runs ONCE when the board powers up or resets

  // Initialize pin modes, serial communication, etc.

}

void loop() {

  // Runs REPEATEDLY forever

  // Main program logic goes here

}

Note: Both setup() and loop() must always be present even if empty.