As most familiar with search engine optimization are already familiar with, there are hundreds of factors that popular engines use in determining which web pages reach the top of their listings.
Some of these factors have stayed true to form over the past two-plus decades, while Google, for example, seems to alter what variables weigh into search engine performance on a regular basis.
Website security is an age-old concept, although Google and competing search engines have recently placed a great deal of emphasis on the security of websites. Pages that have HTTPS- connections, in which all transfers of data packets are encrypted, regularly receive better results on Google than those with basic, now-outdated HTTP- connections.
Obtaining an SSL certificate, a tool that allows your website to run with an HTTPS- connection, although they're often expensive and difficult to obtain. Running your website with a basic HTTP- connection is certainly easier, although Google - individual users, too - typically takes problem with users utilizing non-HTTPS- connections.
Most web browsers also inform users of whether they're browsing an encrypted or basic, unsafe site. As such, it's common that individuals will take problem with browsing these sites, just like Google began doing not too long ago.
Website owners can either have dedicated SSL certificates - the golden standard of SSLs - or self-signed SSL certificates. The former option is typically thought of as more secure than self-signed versions, although it's possible for website operators to obtain dedicated SSL certificates on their own.
Free SSL certificates haven't been definitively proven to have penalties against those websites that use them in terms of search engine optimization performance, although it's a better idea to secure a proper, dedicated SSL certificate for your website.
One drawback to using free SSL certificates is not being able to claim business validation or extended validation, or those websites that feature a green address bar, proving they're encrypted and of the utmost security. They also have to be renewed every month. You could easily forget to renew, then be penalized as a result.
Dedicated SSLs last years at a time - it's better not to skimp, as there's no doubt a dedicated SSL will feature zero SEO penalties.