This is an area of the left temporal lobe of the brain involved in language comprehension. It was identified in 1874 by German neurologist Carl Wernicke. It receives input from the primary auditory cortex when listening to speech, and from the primary visual cortex when reading. It connects to Broca's Area (involved in speech production) via the arcuate fasciculus pathway. Damage to Wernicke's area can result in fluent aphasia: an inability to produce coherent speech, and an inability to comprehend language.
          Brain
          ___----__
       _--    \ 2  ---_
      /   1   /        \
     |     _B_\       3|
      \  _/     W     _/
       \/__ 4   ___--- 
           -----
1. Frontal lobe
2. Parietal lobe
3. Occipital lobe
4. Temporal lobe
W. Wernicke's area
B. Broca's area