The viewport is defined as the area visible to a user. Obviously, with the number of desktops, laptops, tablets, and mobile devices available, the viewport varies by device and across manufacturers. Before the rise of mobile devices, screen dimensions were static, so there was no need to really consider anything different. But as time went on, it became more important for websites to automatically scale web pages down to the correct dimensions, based on the user’s device, so that they did not have to scroll horizontally and try to move through an entire web page made for a desktop screen.
Specify a Viewport for Mobile Browsers (Deprecated)
What is a Viewport?
How to Specify a Viewport for Mobile Browsers
Specifying the viewport for mobile devices consists of a viewport meta tag that web developers can utilize how the browser should scale and display the page. Today, this is more commonplace, which is why this specific message has been deprecated, but nonetheless, if you are ever reviewing your site on a mobile device and something does not look right, it is due to this meta tag. While this optimization can be time-consuming to carry out, leaving this unchecked can result in images that are set beyond the viewport dimensions and cause a less than ideal user experience. While many speed tests will only check to see if the viewport meta tag is present, it is always best to check how your pages look and function across different devices after making the page live or even making normal, frequent updates, especially if you have many people that access and work on your website.
Lighthouse is an open-source tool that is used to run an audit against your web pages and provides scores and suggestions for improving page performance, accessibility, SEO, and more.
PageSpeed Insights is a tool created by Google that reports on the performance of a page on both mobile and desktop devices, and provides suggestions on how that page may be improved.