When it comes to computers, it’s better to be safe than to risk losing or exposing your data. One of the simplest and most reliable ways to protect your Mac and all the information it contains is to lock it with a solid password.
It’s not enough to log off your Mac
Some people “lock” their Mac computer by logging off or shutting down the device.

You know the difference between a good password and a bad one. Many of us do like the convenience of a simple, easy-to-remember password that requires no effort to recall and type when we connect to our WiFi network, buy from our favorite e-tailer or use for online bill pay.