Mobile Friendly vs Mobile First vs Mobile Responsive

Selected answers from the Dumb SEO Questions Facebook & G+ community.

• 
  Micah Fisher-Kirshner: Re: CSS Display None for Mobile: For now this is not a problem, however, when Google switches to a mobile index, then any content that is hidden where a user cannot get to via some sort of interaction (i.e.: click), then that content will not be valued in their algorithm/ranking.
• 
  Webado C Webada: 1. Mobile Friendly is a general term concerning a website. It is or it is not mobile friendly, it works properly or not on mobile devices. 2. Mobile First refers to how Google assesses and ranks websites which are also mobile friendly. The rank in search results even for desktop searches will be based on the rank of the site on mobile searches. Sites which are not mobile friendly are not directly affected on desktop searches but will be overtaken by a site of comparable quality and relevance which is also mobile friendly. 3. Mobile Responsive refers to one of several methods used to make a site mobile friendly. The url and content of each page is the same for desktop and mobile, the display is adapted to the device via css media queries rules, thus the page is deemed responsive. Other methods involve having different urls for desktop and mobile or serving different content dynamically for desktop and mobile on the same url. I expect you need to be mindful of the Wordpress theme and plugins you use that attempt to make the site mobile friendly. If the method used creates a responsive theme, having sections of content hidden with css for mobile or desktop versions using media queries is normal. Yes, some of the html markup may be doubled up, but the css determines what is visible and when. It`s not a matter of repeated content when media queries control css. But it may add to the bulk of the page. For instance if for desktop you show a large image file and for mobile a smaller version image file, both images are in fact loaded when the page is accessed so the total size of the page is affected.
• 
  Webado C Webada: Not in the case of css and media queries. As long as all the content is comparable between desktop and mobile of course, I assume you`re not going to spam by hiding content that way.