Based upon diverse resources drawn from cybernetics and systems theory to structuralism and narravitity, systemic thought evolved from an ecology of mind freed from undue recourse to individual psychopathology. Contemporary systemic thought relies heavily upon social constructionist thought - where meaning and realities, in the social realm, are seen to be co-constructed. Systemic therapy garners from a very broad corpus of literature concerned with how families, couples, children and groups are structured and function. Difference is seen as information and, information of difference is viewed as knowledge about a system. Therapy sessions use interventive questioning techniques to stimulate individuals, couples or family groups toward lasting change. Systemic thought is composed of many relational sub-disciplines, for example: structural therapy, strategic therapy, solution-focused therapy, Milan therapy, post-Milan therapy, emotional-focused therapy, narrative therapy and attachment-narrative therapy.