Politeness theory, developed by Penelope Brown and Stephen Levinson, is a key aspect of pragmatics that explores how individuals strive for politeness in communication to maintain social harmony. The theory distinguishes between two types of 'face': positive face, the desire to be liked, and negative face, the desire for autonomy, with strategies like positive politeness and negative politeness reflecting these needs. The document outlines various face-threatening acts and four main politeness strategies used in social interactions to ensure respectful communication.