information:highlighting
Control units

Most prisoners are part of the "general population" of the prison, members of which are generally able to socialize with each other in common areas of the prison. A control unit or segregation unit (also called a "block" or "isolation cell") is a highly secure area of the prison, where inmates are placed in solitary confinement to isolate them from the general population. Other prisoners that are often segregated from the general population include those who are in protective custody, or who are on suicide watch, and those whose behavior presents a threat to other prisoners.