p5.js is a JavaScript library that starts with the original goal of [Processing](http://processing.org"), to make coding accessible for artists, designers, educators, and beginners, and reinterprets this for today's web.
Since p5 is a JavaScript library, you should learn [Javascript](https://learnxinyminutes.com/docs/javascript/) first.
```js
///////////////////////////////////
// p5.js has two important functions to work with.
function setup() {
// the setup function gets executed just once when the window is loaded
}
function draw() {
// the draw function gets called every single frame. This means that for a frameRate(30) it would get called 30 times per second.
}
// the following code explains all features
function setup() {
createCanvas(640, 480); // creates a new canvas element with 640px as width as 480px as height
background(128); // changes the background color of the canvas, can accept rgb values like background(100,200,20) else grayscale values like background(0) = black or background(255) = white
}
function draw() {
ellipse(10,10, 50,50); // creates a ellipse at the 10px from the left and 10px from the top with width adn height as 50 each, so its basically a cirle.
//remember in p5.js the origin is at the top-left corner of the canvas
if (mouseIsPressed) {
// mouseIsPressed is a boolean variable that changes to true if the mouse buttton is pressed down at that instant
fill(0); // fill refers to the innner color or filling color of whatever shape you are going to draw next
} else {
fill(255); // you can give in rgb values like fill(72, 240, 80) to get colors, else a single values determines the grayscale where fill(255) stands for #FFF(white) and fill(0) stands for #000(black)
}
ellipse(mouseX, mouseY, 80, 80);
// mouseX is the x-coordinate of the mouse's current position and mouseY is the y-coordinate of the mouse's current position
// the above code creates a circle wherever mouse's current position and fills it either black or white based on the mouseIsPressed
}
```
## Further Reading
* [p5.js | get started](http://p5js.org/get-started/) The official documentation
* [Code! Programming for Beginners with p5.js - YouTube](https://www.youtube.com/watch?v=yPWkPOfnGsw&vl=en) Introduction and Coding challenges using Processing and p5.js by Coding Train
