This chapter discusses the concepts of unilateral acts, acquiescence, and estoppel, and the relation between the three. All three are rooted in the principle of good faith, but unilateral acts are in their essence statements or representations intended to be binding and publicly manifested as such, whereas acquiescence and estoppel are more general categories, consisting of statements or representations not intended as binding nor amounting to a promise, whose binding force depends on the circumstances.