Add a password to a PDF so it can't be opened without it — useful before emailing sensitive documents.
There's no recovery — keep the password somewhere safe, since a forgotten password makes the file permanently inaccessible.
No — the password isn't retained after your file has been processed, and it isn't sent off your device, since the encryption happens in your browser.
Send it through a different channel than the file itself — if the PDF goes by email, share the password by phone or message. Emailing both together removes most of the benefit of protecting the file.
Length matters more than symbols. A few unrelated words strung together is both harder to guess and easier to pass along than a short scramble of characters.
This tool sets the password required to open the document. Once someone opens it with that password, they have normal access to the contents.