Borders are present in each form of human activity. Probably the most common representation of border is the separation, yet borders are implied in many operations enabling development, action, thinking, sense-making and relation-making. In this work, borders are considered as dynamic semiotic devices enabling many functions relevant for each living organism and psychic systems as well. Taking into account several border-focused models from psychoanalysis, psychology and semiotics, the author identifies and discusses eight operations carried out by borders: Distinction, Differentiation, Separation, Containment, Protection, Mediation, Transformation and Regulation. Each function is not mutually exclusive but it is recursive in time and works respect to intra/inter-subjective contextual conditions.