Anxiety can have a profound impact on life and can be observed in every child as early as the first months of life (see stranger anxiety). Anxiety is a response to an actual or imagined threat. A distinction is made between the current emotion of anxiety (state) and the personality trait of anxiety (trait). Anxiety can manifest in various forms; for example, Riemann distinguishes between four basic forms of anxiety: fear of self-surrender, fear of self-actualization, fear of change, and fear of necessity. In addition to these basic forms, there are other types of anxiety, such as evaluation anxiety or stranger anxiety. Anxiety serves to help us recognize dangers and respond to them appropriately, either by fleeing or fighting. Fear can be understood as a motive for avoidance. In addition to psychological aspects (such as classical conditioning), biological processes (the sympathetic and parasympathetic nervous systems) must also be considered in the development of anxiety.