A messaging app called Signal based in San Francisco was used by the Trump administration to discuss war plans.

With news this week of the messaging app being used to discuss war plans, we get you up to speed on what Signal should be used for—and what it shouldn’t.

Typically, I assume, those sorts of conversations aren’t had using consumer messaging platforms on the Secretary of Defense’s iPhone. Also, I sort of assume that the people involved are smart enough and tech-savvy enough to notice that a journalist has entered the group chat.