Until now, Google has only had one index, and it focused on crawling sites built for desktop computers.

Recently, Google has shifted its focus to mobile users, who have already outpaced desktop users around the world. Instead of merely factoring in a site’s mobile responsiveness in its overall page ranking, Google has announced that it will create a mobile first index specifically for these users.

Already, marketers are scrambling to figure out what this will mean for their sites and their livelihoods. Here’s what we know:

Mobile and Indexing

First, it is important to understand how indexing works and why it’s important.

You have likely come across mentions of these concepts in your marketing research, but unless you like to savor the technical details, you have probably glossed over it.

To determine what pages to shows users when they search, Google crawls websites to collect information about what they offer overall and what individual pages offer specifically. Crawling also gives Google information about the “rules” on your site, such as what pages should be blocked, what links should be followed or not, and so on.

Google then sorts the information and stores it in its database in a process called indexing. The search engine also makes a copy of pages in a usable format for its algorithm.

Since Google only has a desktop index, it looks at relevant results when a mobile user searches for something. It then sees if there are any mobile signals from that site and may adjust the results accordingly.

This causes problems because users are often shown rich snippets from the desktop content, which may not be available for mobile users. Or marketers may have capitalized on this glitch and used it to redirect people to their app or even to a popup asking them to sign up for their email list.

Google hopes to prevent these issues by determining what content is relevant to mobile users only and then indexing and ranking sites accordingly.

How It May Affect Sites

How the mobile first index may affect websites depends on what kind of site they have. They may have a site that is responsive to show up on mobile devices correctly, they may have a dedicated mobile and desktop site, or they may not have a mobile site at all.

Many sites have chosen to use a responsive design so that their site shows up appropriately no matter the device the reader is using. For brands that use a responsive site design, pretty much nothing will change with the mobile index.

Some experts speculate that different emphasis on certain tabbed content or drop-down menus may affect ranking, but no other changes are expected.

Sites that have dedicated mobile and desktop sites will need to ensure that all their important content is on their mobile site not to be affected by the new index. Google will only crawl the mobile site for the new index, so if some content is only on the desktop site, it won’t be seen in the new index.

Ideally, you should already have all that content on your mobile site, so this shouldn’t be an issue. If you don’t, now is the time to start importing that content and getting it published.

Brands that don’t have a mobile site don’t have to panic. The search engine will still crawl the desktop site to rank in the mobile index. Sites that are not designed specifically for mobile audiences won’t rank as well, but they won’t be left out in the cold.

If you don’t have a dedicated mobile site or a responsive design, now is the time to get one. You won’t become invisible in the new mobile index, but you also won’t rank as well as you could have.

Moving Forward

Though news of the mobile index has created a lot of chatter and worry, there’s really not much to do to get ready.

If you already have a mobile site or a responsive design, you don’t actually need to do anything. If some of your content is missing from your dedicated mobile site, you’ll want to transfer that over, but otherwise, you’re all set.

If you don’t have a mobile site, the least you need to do is make your site responsive. This is easy enough with the help of a web developer or a new WordPress template. You can take the opportunity to give your site a bit of a design overhaul and attract some new readers. Your site will look nicer, and you can improve the SEO while you’re at it.

When you’re looking at where content is missing on a mobile site, you might also realize that you need to revamp your site architecture. Perhaps you were leaving it out in mobile because the information wasn’t organized very well to begin with and didn’t make sense where it was.

Get ready for mobile and make your whole site better in the process.