The Viewport refers to the user’s visible area of a web page. It varies with the device being used.
For instance, the Viewport will be smaller on a mobile phone compared to a computer screen. Before the of invention of tablets and mobile phones, web pages were designed exclusively for computer screens, often with a static design and fixed size.
However, when people started accessing the internet using tablets and mobile devices, fixed-size web pages became too large to fit the smaller Viewports.
To address this, browsers on these devices scaled down the entire web page to fit the screen, although this solution wasn’t perfect.
To gain better control over the viewport, HTML5 introduced the <meta> tag, which allows web designers to set instructions for how the browser should handle the page’s dimensions and scaling.