What does the US secret service do?

Question

are they are secret police or somthing?

Answer 1

They protect the president, VP and certain administration members.

They also investigate terrorism

And they investigate all money crimes, counterfieting, etc.

Answer 2

They protect the president, they also investigate counter fitting.  That is what they originally founded for, to combat counter fitting.  They  also tracks suspicious people and investigates a wide variety of financial fraud crimes and identity theft.