Apps here have been through automated and human checks before you can install them. That gate is most of the reason your phone is safer than your laptop.
The drawing that proves the sentence above. It is the same card that is in the book.
Think of it as
a licensed bazaar with a gate.
For example
Everything you install comes from one place that checked it first. That gate is most of why your phone gives you less trouble than your laptop.
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.