Embedded links are to the most relevant part of videos, articles, etc.
Following abbreviations are used:
Mobile Friendly→MF
Mobile-Friendly test tool→MFT
PageSpeed Insights→PSI
TL:DR
- This algorithm affects entire world, and the impact will be large.
- This algorithm works page-by-pages, not site-wide.You don't have to make whole your websites MF. Prioritize and make the most important pages for you and mobile users MF.
- This algorithm works only on mobile searches. It doesn't affect desktop searches.
- At the moment, the rule of this algorithm will be quite simple. If a page pass MFT, the page get boosted. If not, it doesn't. There aren't any grays - just black or white.
- Non-MF pages are not relevant to mobile search. So MF or not will affect your ranking visibly.
- Too heavy CSSs can harm you as MFT times out. Make it light - it also is good for pagespeed.
- To get MF boost, avoid blocking Googlebot crawling onsite CSS/JS.
Helpful webpages:
Tools:
MFT
-The most suitable tool if you focus on Google SEO.
PSI
-If you focus on user and SEM, this tool will help a lot.
Documents:
Webmaster's Mobile Guide
-General guide telling what to do and what to avoid.
PSI Rules
-Detailed criteria of MF judgement.
Affects globally, and impact will be big.
"This change will affect mobile searches in all languages worldwide and will have a significant impact in our search results." - Webmaster Central Blog"Thomas Goering:
Will the Mobile Friendly ranking factor be lightweight and barely detectable in the beginning with the option to make it stronger over time -- much like the HTTPS ranking factor, or will it be online and full throttle from day one?
John Mueller:
it'll be quite visible." - John Mueller
Affects only mobile search, not desktop search:
"And the question is pretty much about will the ranking changes only affect my website for mobile searchers or also for desktop searches? So the answer to that is only for mobile searches. So don't be afraid. On the 21st of April, there will only be an update taking place for your search results in mobile, which means that desktop will stay the same as it's working right now. This does definitely mean, though, that you should pay attention to the mobile search results, as this is something that people are using more and more." - John PutsPassing MFT = Regarded MF by Google = Boosted in mobile search
"put in your website there (=MFT). And you will directly see whether Google sees your website as mobile friendly or not." - John Puts* "webpage"s in this statement seems to be mistakes of "webpage".
Not MF = Not relevant in mobile search.
We just established, as the bare minimum for you to be competitive and for Google to consider that your website is relevant in a mobile world...So I would say that the mobile-friendly testing, the mobile-friendly badging, as of now, looks at the must-have features for websites, for us to consider them mobile friendly. - Diogo BotelhoRule is binary. Boosted when passing MFT and get MF badge, and vice versa.
"So at the moment, it is a binary decision in the sense that if you are awarded the mobile-friendly badge, it means that you pass the test, which means that we consider you mobile friendly. And it's based on a couple of the requirements that we mentioned. And that if you don't pass the test, we highlight and help you sort out. So at the moment, it's not gray. And there's not various degrees of how much you can benefit from this ranking factor. It's really do we consider you to have the minimum requirements to provide a good experience to your users on a mobile. If yes, you're going to benefit from this signal, as opposed to websites that don't have this minimum, don't pass this minimum requirement. So, so far it's very binary. " - Diogo Botelho
Page-by-page determination.
"AUDIENCE:OK, so if I just update the new page and, by mistake, I add a banner that might exclude the mobile-friendly tag for just that page, will that page have to suffer-- I mean, not get the benefit from the ranking signal? Would the whole website be affected by this, or just that single page, or not at all?
DIOGO BOTELHO:
No, if you have one, specific page that we would be showing on the search results that is clearly not providing a good experience, made before that banner or not, we will identify that one page as having that issue. But if your whole website-- if the main page of your domain and if the other pages are good, they're not going to suffer by consequence." - Diogo Botelho
"When determining if a page is mobile friendly, Google bases this on a page by page case. So passing some pages, or even most pages, as mobile friendly will not mean your entire site passes the check. All pages must be mobile friendly." - Gary Illyes
Pagespeed is a small ranking factor, as it has been said over years.
"It is a small ranking factor if your website has a better speed or not....And this tool (=PSI) will help you directly getting good information about how well are you doing on speed." - John PutsToo much CSS can cause failing in MFT, as MFT times out.
"Ken Hirooka:A JP webmaster reports that he failed in mobile friendly test due to number of CSS.
He used 20 CSS on a page when failed, and as he compressed it into 10 the page passed the test.
Are there maximum number of CSS googlebot can read?
John Mueller:
No, Googlebot will cache the CSS files and keep trying until it has them all. However, the testing tool times out after a certain time, and that's probably what's happening here. Fewer CSS files is always good, especially on mobile sites - each additional file takes a lot of time to download on a phone. However, it's not required in this specific case." - John Mueller
Improvement on your pages will be reflected soon as it's real-time algo...
"Gary explained that the algorithm runs in real-time, so technically, you can do it any day, and as soon as Google picks up on the change, the site will start to benefit from the new mobile-friendly algorithm change." - Gary Illyes"Illyes says “As soon as we discover it is mobile friendly, on a URL by URL basis, it will be updated." - Gary Illyes
... so asking for crawls on improved pages will help you.
"Ken Hirooka:in EN example, the webmaster clearly reports that he got Mobile Usability error message on URLs which passed MFT. Isn't it inconsistent?
John Mueller:
Their robots.txt file changed significantly recently, that would be my guess. If css/js is blocked from crawling, we can't see the page as mobile-friendly. If you change that, it'll still take a while for all of that to update. Not mentioning these kinds of changes in the thread doesn't really help." - John Mueller
"Illyes says “As soon as we discover it is mobile friendly, on a URL by URL basis, it will be updated." - Gary Illyes
To get MF boost, avoid blocking Googlebot crawling onsite CSS/JS.
"If you are blocking elements such as CSS and javascript, your site will not pass Google’s mobile friendly test, even if everything else on the site passes. So you do need to allow Googlebot to crawl both CSS & javascript to pass."- Gary Illyes
"What about offsite resources that may block javascript?
Because webmasters don’t always have control of offsite javascript – for example Google Analytics code – so Google takes this into account. But Illyes does stress again that webmasters need to allow Googlebot to crawl javascript and CSS on their website itself."- Gary Illyes
