The FBI could be your friend and you'll never know. When people tell you that the F.B.I. is good at undercover work, they’re really saying is that you can count on the bureau’s operations to result in an arrest or the prevention of a crime, more often than not. Undercover officers are trained to assume false identities, and to spend years developing information.

They are frequently placed within criminal organizations to monitor or develop cases. Such work requires patience and preparation. The F.B.I. has tools to assist with this, like the ability for surveillance, the legal support for doing so and access to national databases.

Some of its undercover work has been praised for preventing serious crimes, such as large scale plots of terrorism or drug trafficking operations. The cases are typically complicated and require coordination among agents, prosecutors and other law enforcement organizations. Undercover work can also be controversial, with some objecting to when they believe the FBI crosses a line or entices criminal activity in order to make an arrest. That is what is known as entrapment, and courts carefully scrutinize such instances to determine whether a person was induced to do something they wouldn’t have otherwise.

And you don't, as a reminder, want to end up in harm's way, because undercover can be hazardous. Agents sometimes play-act for months or years as someone else. That can result in stress or possibly danger. Even so, the FBI has a long history of employing the method to gather evidence that is admissible in court.