What Is Mobile First?
As of March 2018, Google started slowly implementing their “Mobile First” algorithm into it’s search engines.
"In a nutshell, Google Search now prefers and now craws the web looking for sites that load faster & perform better across mobile, tablet & desktop devices."
This change in Googles algorithm is causing sites to lose search rank if they are not build to benefit the Mobile First Indexing algorithm. It is a change that makes it imperative for website owners to have the best performing sites on ALL devices.