The advertised speed is a shared maximum, not a promise. For video calls the number that matters is upload, which is usually a small fraction of the download figure.
The drawing that proves the sentence above. It is the same card that is in the book.
Think of it as
a wide highway, with a narrow lane coming back.
For example
You do not dial anything or wait to connect. You open the laptop and it is already online, the same as the lights being already on.
This is one card out of 275.
The hundred words you meet most are free — the whole set, animated, in one file that works with no internet.
Volume 1 has all 275 in fifteen chapters, with Staying Safe the largest chapter on purpose.