So essentially an SSL establishes is an encrypted link between your web server and your visitor’s web browser. This ensures that all data passed between the two remains private and secure.
Sure you have browsed the web and you have most likely seen that when you access certain pages, a pop-up window appears that says the site is not secure, stating “are you sure you want to visit this site?” Then you must press yes or no. It's a common message that pops up if you do not have an SSL.
In the past, the only time that you needed to care about SSL was an eCommerce site but that all changed when Google announced that an SSL was going to be rolled out as a ranking factor.
So, sites that use SSL certificates will get a boost in the search rankings. It might not be a huge boost, but I think you’ll agree with us that any boost in search rankings is a good one.
But now Google has gone even further and will now mark “HTTP” pages that collect passwords or credit cards as non-secure.” That means your WordPress login page will be marked as non-secure if you’re not using HTTPS.