What is HTTPS
Hyper Text Transfer Protocol Secure (HTTPS) is the secure version of HTTP, the protocol over which data is sent between browser and the connected website. The 'S' of HTTPS stands for 'Secure'. It means all communications between browser and website are encrypted.
HTTPS is now the norm
HTTPS is often used to protect highly confidential online transactions like online banking and online shopping order forms. But has now become to norm.
Https for early-adopters may have given them an advantage on their competitors, these times are over. If you haven't made the transition yet, it needs to be very high on your priority list. Since summer 2018, Chrome now shows a not secure warning so beware of a sharp increase in bounce rate should you now have implemented it yet, on top of lower rankings.
Plan your site migration carefully, including identifying pages to redirect (which should be the most valuable ones), and those you should not. Timing is key to avoid risks, so avoid doing it before your high season.