Why is a login with a password used for authentication instead of a single password?

Question

User identification

What system do not come in - everywhere they use at least a bunch of login + password.
Why not just use a password? After all, it's easier. You still have to remember it somewhere.
Or are there any pitfalls?

Answer 1

Multiple users can have the same passwords.

Answer 2

Well, something like this
Click the replace button .. replace tab
Insert into find

(\+\d\s\d+\s\d+-\d+-\d+)(.*)(\+\d\s\d+\s\d+-\d+-\d+)(.*)(\+\d\s\d+\s\d+-\d+-\d+)(.*)

Paste in replace \1\n\3\n\5
Click replace all