Early last year was yet another update from Google for its search engine algorithm; this time specifically focused on mobile friendliness. Industry term coined was Mobilegeddon. We have been discussing about search algorithms and updates in last few posts. Here are some of the updates we discussed so far --
In the last post, we briefly touch based on what app indexing is how important it is? Last year, in April; Google updated the algorithm component (mobile-friendly algorithm update aka Mobilegeddon) to consider mobile friendliness / app indexing as a search ranking signal. Inclusion of factors involved in mobile friendliness to show the search results of normal websites was also part of this update. Mobile friendliness is captured on a page by page basis. So you will not be penalized at a website level if some of web pages are not mobile-friendly. It's just that only mobile-friendly web pages have better chance of showing up with a better search rank compared to non-mobile friendly pages. Also it has affect only on mobile search; not the usual desktop based searches.
How are doing with mobile friendliness?
If you would like to see how well you are doing in terms of mobile friendliness from Google's PoV, do check out this tool - Mobile-Friendly Test (though take this with a pinch of salt since some results may be flawed). A better approach would be to go through all your issues in Google Webmaster tools especially starting with mobile usability feature. Another option to see if you have a mobile friendly site is to search for the website directly in your mobile. If the search results show a prefix - 'Mobile Friendly'; it means you are good! Google claims even using Chrome's autocomplete feature puts you in a better chance (!!!)
What this update means from a SEO perspective?
Unfortunately, there is no easier fix for this. It goes to core of web design. You have to choose between high level decisions of having a responsive design to having a separate mobile website. Here is a great guide on Mobile SEO and design from Distilled. Google also provides some of the mistakes folks make while trying to be more mobile friendly. Another potential that can be undertaken is to follow the schema.org template. This also helps from a semantic search perspective.
Does only Google cares about mobile-friendliness?
No. Bing has also been making updates to its algorithm to factor in mobile friendliness. Bing also uses a 'Mobile Friendly' tag to notify users that a web page is mobile friendly.