Fear is the main source of social and political control in the Republic of Gilead, the society of The Handmaid's Tale. Offred, the main character, is hemmed in by fear all the time. When she goes to market with a fellow handmaid, she confronts the dangling dead bodies of people who have been hanged for crimes such as sexual deviancy. When being trained as a handmaid, she lives in fear of the harsh physical punishments the smallest lack of obedience brings. Living in the commander's household, she lives in fear that if she does not get pregnant, she may be sent to the colonies to clean up radioactive waste: a death sentence.
Lack of any information about what is going on in the wider world also feeds the fear of Offred and the other handmaids. They simply have no information with which to orient themselves to a wider world, so must always assume the worst as a default position.
Offred and her fellow handmaids are under almost constant surveillance. Armed guards control the streets, and spies work undercover. Offred must stay in her own world and is afraid even to ask questions for fear that she will be denounced.
The highly restricted world that Offred lives in provides a backdrop of constant anxiety, especially as she often has nothing to do. The novel effectively shows that the everyday knowledge, mobility, and information...
we take for granted are sources of power that are denied to the lower caste women in this society. Beyond that, the constant and ever-present threat of severe physical harm or execution keeps people in line in an inhumane environment that no normal person would tolerate if he or she had a choice.