The document discusses grand nursing theories, which attempt to broadly explain areas within the nursing discipline. It describes three main categories of grand nursing theories: human needs theories, which view humans as reducible parts and focus on meeting needs; interactive theories, which see humans holistically interacting with their environment using systems theory; and unitary process theories, which view humans as unitary energy systems constantly interacting with their environment in unpredictable ways. Examples of theorists within each category are provided.