The canvas tag is a container used to draw graphics on a web page with the help of JavaScript. It was introduced in HTML5 and allows for dynamic and scriptable rendering of 2D shapes and bitmap images. It can be used to create animations, games, data visualization and image manipulation on the web in real-time. The canvas element itself is just a drawable region, and actual rendering has to be done with JavaScript.
Example:
```
```
In JavaScript creating a simple rectangle would look like:
```
let c = document.getElementById(“myCanvas”);
let ctx = c.getContext(“2d”);
ctx.fillStyle = “#FF0000”;
ctx.fillRect(0, 0, 150, 75);
```
