Neurodegenerative disorders are progressive diseases characterized by loss of specific neuronal populations followed by a clinical picture of a different neurodegenerative entity. Current classification of these diseases respects the names of the main pathophysiological processes involved in the groups of disorders. This is the reason why key proteins which represent neuropathological and biochemical hallmarks of diseases are found in their names. Neuropathological diagnosis is a synthesis of neurohistological changes in the brain and spinal cord and identification of pathological proteinaceous aggregates in neurons and/or glial cells. These inclusions are predominant diagnostic micromorphological and biochemical markers of disease. In the text, there is a brief summary of current knowledge about pathophysiology of neurodegenerations and diagnostic criteria for the most frequent entities.