Many websites are now viewed on mobile devices. The viewport enables your pages to be optimised to be viewed on different devices.
If a customer views your page on a mobile or hand help device you want the page to be optimised viewing for that device. A page with no viewport for a mobile device would render the desktop size which may make text, buttons and images hard to read.
To optimise the viewport for mobile devices your pages should include a meta viewport in the <head> section of your page specifying width=device-width, initial-scale=1. <meta name=viewport content="width=device-width, initial-scale=1">. If you using a content managing system (CMS) or e-commerce software check with your software supplier for details. Alternatively, you can work with a web developer to make the changes to your web pages.