Https is the protocol that secures the conection between your device and the websites servers, it also vailidates that the server you think your comunication with is genuine.
A TLS certifcate is signed by a trusted 3ed party called a CA {Certificate Authority} eg. GlobalSign, Let's Encrypt or like in the case of my site Cloudflare.
here are some rules of thumb to keep you save when browsng the world-wide web.
Always use look for the padlock icon or in chrone the horizontal lolly pops or in the beginging of the URL https://
Never submit sensitive information over a non https conection.
Look for the latest verison of TLS Transport layer security {the protolcol that does the encryption} latest versions are 1.2 and 1.3 as of this post.
4.avoid mixed content this when a website is serving up content over https and not secure http
always look for trusted certificates some websites may still use certifcates that are decomisstioned and no longer trusted or self signed certifactes though this is rare.