SSL is today widely used Encryption Security Technology specially case in Online Transaction.. If you are confusing then don't worry. I solve your confusion. Ok.
When you did completed your shopping from online website then after you have to need completed your transaction
with your Internet banking and credit cards etc. So when you do online transaction then you need to check page url in your browser address bar. This url start with HTTPS .
HTTPS provides online authentication of the website and associated web server that one is communicating with, which protects against man-in-the-middle attacks and secure your transaction and save your information as well as money.
Now Google Top Search Engine like to give priority to HTTPS website specially for SPAM. So they updating their algorithm in order to minor boost-up to https website.
So if you are doing search engine optimization then you need to more concentrate on https website only for year then after we don't know what google's plan. Also if your https website and page is block throught robots.txt then remove this https website from robots.txt file and also avoid no-index meta tag.
For More Information Please Visit :- Google To Give Secure Sites A Ranking Boost