At the close of last month's Search Marketing Expo (SMX) West, conference speakers were asked to share their key takeaways.\n\n\n"Mobile, mobile, mobile," said Kelly Wrather, senior manager of content marketing for Kenshoo and an SMX presenter. "I want to grab every website designer and tell them mobile is the thing! It's the only thing!"\n\n\nAt previous SMX shows the importance of mobile-optimized websites was a frequent topic of discussion, but this year, as Wrather's declaration illustrates, there was a sense of urgency because "Mobilegeddon," as some are calling it, is nearly here.\n\n\nOn April 21, Google will expand its "mobile-friendly" search result rankings, and the company says the changes will have an even bigger impact on search than its past Panda and Penguin algorithm updates. The Penguin update affected about four percent of global searches, and Panda impacted about 12 percent of English-language searches, according to Search Engine Land, so the new mobile-friendly update has the attention of everyone in the SEO community right now.\u00a0\n\n\nHere's what you need to know to prepare for Mobilegeddon.\n\nMobilegeddon, and how we got here\n\nA website mobile-friendliness has been a search ranking factor for two years. The April 21 algorithm change means mobile-friendliness will become an even more important ranking factor, according to Jayson DeMers, founder and CEO, AudienceBloom. "Websites that aren't mobile-friendly will see a more negative impact in search visibility than they may already be seeing, and mobile-optimized sites may be rewarded even greater in search rankings," DeMers says.\u00a0\n\n\nIn June 2013, Google wrote on its Webmaster Central Blog that it planned to roll out "several ranking changes in the near future" to "address sites that are misconfigured for smartphone users."\n\n\nAt that time, Google outlined two typical mistakes that can cause websites to deliver poor mobile experiences: faulty redirects for site pages listed in search results that send smartphone users to a single mobile page, such as the home page, instead of a mobile-optimized version of the page users want; and smartphone-only errors, which occur when smartphone users click Web pages listed in search results and only see error messages.\n\n\n[Related: SEO and SEM predictions and tips for 2015]\n\n\nMore recently, on February 26, 2015, Google announced via its Webmaster Central Blog two "important changes to help users discover more mobile-friendly content" on their mobile devices.\n\n\nThe first change, coming on April 21, will be to deliver "more mobile-friendly websites in search results" on mobile devices. With this update, the search giant will expand its use of mobile-friendliness as a ranking signal, and it will affect mobile searches "in all languages worldwide."\n\n\nGoogle's mobile-friendly algorithm will "have a significant impact in our search results," giving mobile users easier access to "relevant, high-quality search results" optimized for mobile devices, the company says.\n\n\nAs for the second change, Google also announced in February that apps indexed through Google App Indexing would immediately begin ranking higher in mobile search. So if you're signed into your Google account, content within the apps on your mobile device will rank higher in search results than it would have ranked previously.\n\n\nFor example, let's say you have the OpenTable app installed on your Android smartphone. Using that same device, you perform a Google search for a restaurant. If that restaurant is listed on OpenTable, a "deep link" to its page in the OpenTable app will be included prominently among the other search results. Currently, Google App Indexing only works on Android. For more details, check out Google's App Indexing for Google Search pages for developers.\n\nWhat you should know moving forward\n\nGoogle's mobile-friendly algorithm "will be a page-specific influence, meaning that if some pages on a specific site are mobile-aware and others aren't, those with the mobile-friendly design will get a boost on mobile searches," says Thomas Petty, president, Bay Area Search Engine Academy.\n\n\nThe new algorithm will give mobile-optimized pages an "instant" boost in search results, according to Petty. "If Google has previously indexed your site, and your site wasn't mobile-aware at the time, and the next time Google comes to a specific page of your site that now is mobile-aware, that page will get an instant boost in mobile searches," he says.\n\n\nGiven how much emphasis Google is placing on mobile-friendliness, the algorithm could also directly or indirectly impact desktop search result rankings right away, or at some point in the future.\n\n\n"Google has been notifying website owners for several months now in Google Webmaster Tools if their website isn't mobile-aware," Petty says. "I believe mobile-awareness will continue to be an influence on the good experience that Google wants users to have on all the various devices we carry."\n\n\nVisibility in mobile search results could inadvertently impact desktop search rankings, according to DeMers. "The most significant current ranking factor is quality and quantity of inbound links to a website or page," he says. "One of the ways websites accrue inbound links is through their content being linked to as a resource."\u00a0\n\n\nIf journalists, columnists, bloggers and others who are likely to link to that content can't find it on mobile devices, the content may not acquire as many links as it might have otherwise. Fewer links could therefore diminish content search rankings in desktop searches as well as mobile. "So a lack of visibility in mobile searches might negatively affect desktop search visibility as well," DeMers says.\n\n\nGoogle algorithm updates also tend to penalize sites "across the board," says Arham Khan, senior digital marketing executive, HighQ. If a site is penalized for not being mobile-friendly in mobile searches, it will also likely be penalized in desktop searches, he says.\u00a0\n\n\n\t\t\t\t\n\t\n\n\t\t\t\n\t\t\t\tHow to design a mobile-friendly website\n\nThere are three ways to create mobile-friendly websites, according to Petty.\n\n\n1) You can set up a mobile-responsive website design using CSS3, the latest standard for Cascading Style Sheets. Responsive website design, Google's preferred optimization method for mobile device displays, automatically rearranges, hides or displays information across a variety of devices, including desktop PCs and smartphones. "All content is served equally," Petty says. "It's just rearranged or hidden depending upon the device."\n\n\nResponsive design "allows you to make changes in one place and show them across all platforms," says Khan. It's a more elegant, streamlined way to serve mobile content and provides a "great user experience."\n\n\n2) You can create a website that serves different HTML and CSS content and formatting through the same URLs to specific devices. Petty says this approach "is accepted but much more complicated to maintain" than responsive design.\n\n\n3) You can build a separate, mobile-specific website with a different URL, such as m.companyweb.com. This is the least desirable option, according to Petty, because you have to maintain both a mobile and a desktop website. "It's easy for things to get out of sync, and you double your website maintenance," he says.\n\n7 tips and resources\u00a0for mobile-friendly websites\u00a0\n\nThe search experts cited in this story offered a number of tips for organizations and individuals looking to optimize their sites for mobile.\n\n\nIf you're just getting started with mobile optimization, "it's OK to work on key, high-traffic pages first and get them mobile-aware \u2014 especially if those pages are important for mobile search," Petty says.\nIf your website was built using open-source WordPress, as many today are, it's easy to optimize for mobile using plugins such as WPtouch, according to DeMers. Also, some Web hosting services, including HostGator and Bluehost, "offer soup-to-nuts mobile-optimization for clients," he says. "I used HostGator's service recently for my site, and it worked like a charm."\nBusinesses should recognize that they have different audiences on different devices, according to Petty. "Mobile users don't necessarily want to see all the same information a desktop user would see."\u00a0For example, Petty says one of his favorite restaurants has a mobile site that differs from its desktop version, but the mobile site "doesn't have a phone number anywhere. This is a big mistake," he says. "If I'm out walking around downtown with my wife and want to call on my cell to get a reservation, I can't find their number on their site."\nYou should get started now. "It's vital that you optimize your site well before April 21," Khan says, because "Google will need to crawl and index the mobile optimized version of your site, and this takes time. It won't be good enough to make changes the night before the update, as this won't give Google enough time to crawl and index the mobile-optimized version of your site" before the algorithm changes roll out.\nMoz's Mobile Optimization Guide and Google's Mobile SEO guide are also great places to find more details on mobile optimization.\nYou can test your site using Google's Mobile-Friendly Test.\nAnd Google Webmaster Tools users can get Mobile Usability Reports with details on issues that may keep their sites from displaying properly on mobile devices.