Dissection is usually the process of disassembling something to determine its internal structure and as an aid to discerning the function and relationships of its components. It may refer also to some spontaneous natural process of dissasembly as in aortic dissection.
Dissection is usually applied to the examination of plants and animals. The term is also used (less appropriately) to mechanisms, computer programs, written materials, etc., where more specific terms should be used, such as reverse engineering and literary deconstruction. Dissection is usually performed by students in courses of biology, botany and anatomy and in association with medical and arts studies.
Vivisection literally refers to the dissection of a living animal, often for the purposes of physiological investigation. However, in modern parlance the term usually refers to any type of experimentation in which animals are injured, with or without actual dissection.
Dissection is often performed as a part of determining a cause of death in autopsy (on humans) and necropsy (on animals) and is an intrinsic part of forensic medicine, such as would be practiced by a coroner.
For an example of the dissection of a frog see this external link: http://curry.edschool.virginia.edu/go/frog/
Dissection is a well-known melodic black metal band from Sweden; see Dissection (band).