The single setting that decides whether a lost phone is an expensive annoyance or a stranger reading your email, your messages and your bank app.
The drawing that proves the sentence above. It is the same card that is in the book.
Think of it as
the front door, not the safe.
For example
The phone is left in a taxi. With a lock, someone has an expensive brick. Without one, they have your email, your messages and your bank.
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.