Your family needs a code word. Here’s how to set one up tonight.

It takes five minutes, and it might be the most important security step you take this year.

How to choose the word

Pick something nobody could guess. The National Cybersecurity Alliance says to avoid common words, birthdays, and pet names. Agree on it in person if you can. If you can’t, send it through a channel you both already trust, not a random text. Don’t use the same word for different groups, and every few months, ask each other what it is so nobody forgets.

• Who needs one
• When to use it
• If they can’t give the word