Google ranks websites with SSL certificates a little higher than other websites.
A SSL certificate is required for websites that do eCommerce because it keeps your customers personal information and credit card information secure. If you collect personal information from your customers, or if your website is a membership website with access to a password protected area, then a SSL certificate is a good thing to have.
You can tell when a website is secured with a SSL certificate because the HTTP:// becomes HTTPS://. The S means it is secure. For all intents and purposes, HTTPS is HTTP, just the secure version.
It shouldn’t come as a surprise that Google prefers sites that are trusted and certified. This is because users can be guaranteed that the site will encrypt their information for that extra level of security. However, you should understand that getting a certificate can be an involved task (which is why it allows for higher ranking benefits). A SSL Certificate can be purchased through your host.
HTTPS adds security for your SEO goals and website in several ways. It verifies that the website is the one the server is supposed to be talking to, as well as preventing tampering by third parties. It makes your site more secure for visitors. It encrypts all communication, including URLs, which protects browsing history, personal information, passwords and credit card numbers.
HTTPS is not only good for security, but also for referrer data and other SEO strategies. When considering the future of what Google is likely to do with HTTPS, switching over to HTTPS makes sense to keep up with Google. Also, the value of switching to HTTPS is very likely to increase over time.
Although the SEO ranking advantage is small, the security and trust added to the ranking gains make it worthwhile.