Mobile-first indexing, fully implemented by Google as of December 2025, means the mobile version of a website is used as the primary basis for indexing and ranking. This isn’t simply about mobile-friendliness; it’s about Google fundamentally evaluating a site’s content and structure based on its mobile presentation, impacting visibility for *all* users, regardless of their device.

Google’s systems, including the Lighthouse tool now integrated into Google Search Console, assess mobile page experience factors like Core Web Vitals – Largest Contentful Paint, First Input Delay, and Cumulative Layout Shift – which directly influence rankings in Australia. In December 2025, Google’s systems also prioritise sites utilising responsive web design, ensuring content adapts seamlessly to different screen sizes. Furthermore, Google’s indexing systems now heavily favour sites using structured data markup, particularly schema.org vocabulary, to understand content context on mobile. Australian businesses utilising platforms like Siteimprove or Semrush can leverage these tools to audit mobile page speed, identify crawlability issues, and validate structured data implementation. Google has announced that in 2027, further weighting will be given to sites utilising the Page Experience Report within Search Console to proactively address mobile usability concerns.

Essentially, Google’s ranking algorithms now operate by primarily understanding and evaluating a website through its mobile version, making mobile optimisation critical for search visibility.