Thank you, Simon, for a comprehensive explanation that even I could understand (for the most part). I'm doing research on SSL now.
The Apple laptop uses an outdated version of Safari that, as already stated, will not upgrade, although progressively more websites tell me my ability to "do business thereon" will be hampered. Yes, it is mightily hampered. Well, they don't say hampered, but that's the idea.
I use Chrome on my DELL and, apart from the occasional "unresponsive" alert, it is great.
Thanks again for all you and Angharad do, Simon.