Question regariding address bar when on Boatnerd site

[PaulBeesley]

Thank you!

[Guest]

The website uses http and not https. That's why it says it's not secure.

[PaulBeesley]

Recently the address bar, where the url is, on my Safari browser has changed from "Boatnerd.com" to "Not Secure - Boatnerd.com".

This does not happen with Firefox. Its url says "Boatnerd.com".

Can anyone explain the "Not Secure" bit?

Thanks.