Tabbed Content Loaded On-Click Won’t Be Indexed
Content in tabs is fine for mobile as long as it is loaded when page is loaded and not when the tab is clicked on, otherwise it won’t be indexed.
Links Not Visible By Default Will Be Crawled
Links hidden behind tabs will be crawled in the same way as other hidden content.
Content Hidden in Tabs on Mobile Will be Seen by Google After Mobile-first
Content behind tabs (or other types of user interface) on mobile will be seen by Google when Mobile-first indexing is released.
Content that Fades in Onload With ~2s Transition is Not Considered Hidden
Content is considered hidden when it is not visible at all. Content which fades in within a couple of seconds during a transition or is slightly transparent is likely to be indexed. You can test a transition using Fetch and Render.
Hidden Links are Counted
Links which aren’t visible in the rendered page should carry the same weight as visible links.
Content Position Doesn’t Contribute to Weighting
John seems to be confirming that the position of content on a page doesn’t impact the weight, but they do treat hidden or visibly small content as less relevant.
Hidden Content Has a Lower Weight
You can still rank for hidden content, but it’s given a lower weight than visible content.
Hidden Content get Less Weight
Google tries to detect any content which isn’t visible when rendered and give it less weight than content which is visible.
Content Hidden in Tabs Can Be Put Onto Separate URLs
If you have content hidden in tabs, you can put it onto separate URLs.