With the proliferation of mobile devices, it has become imperative for websites to be displayed compatibly on all devices, i.e., "responsive" design. The most basic HTML tag that provides this compatibility is the viewport definition. In this article, we will detail the meaning, function, and reasons for using the <meta name="viewport" content="width=device-width, initial-scale=1.0"> tag.

Code:

<meta name="viewport" content="width=device-width, initial-scale=1.0">

Meaning:
This meta tag instructs mobile browsers on how to size the page.

Parameters:

width=device-width: Sets the page width to the width of the device screen.
initial-scale=1.0: Sets the zoom level of the page to 1 (i.e., 100%) when it is first loaded.

Purpose and Benefits of Use

It is the Basis of Responsive Design
The viewport tag is mandatory to be able to create mobile-compatible designs with CSS media queries.
Portability and Usability Increase
Thanks to the design that fits the device screen perfectly, problems such as scrolling and zooming are eliminated.
SEO Compatibility
Google and other search engines use mobile compatibility as a ranking criterion. If this tag is missing, you may receive "not mobile-friendly" warnings.
Prevents Design Problems
In pages with undefined viewports, texts may overflow, images may enlarge, and the design may be distorted.

Alternative Viewport Settings

Disable zoom:

<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no">

Define minimum and maximum zoom levels:

<meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0">

The <meta name="viewport"> tag is one of the fundamental elements that ensures a website is displayed correctly on mobile devices. As one of the starting points of responsive web design, you should definitely use this tag on every HTML page. Mobile compatibility is critical for both user experience and SEO.