Transpose[list] transposes the first two levels in list.
Transpose[list, , , ... ] transposes list so that the k level in list is the level in the result.
Example: Transpose[a,b,c,d] .
Transpose gives the usual transpose of a matrix.
Acting on a tensor Transpose gives the tensor .
Transpose[list, , , ... ] gives the tensor .
So long as the lengths of the lists at particular levels are the same, the specifications do not necessarily have to be distinct.
Example: Transpose[Array[a, 3, 3], 1, 1] .
See The Mathematica Book: Section 1.8.3, Section 1.8.14, Section 3.7.2 and Section 3.7.7.
See also: Flatten, Tr.
Related package: LinearAlgebra`MatrixManipulation`.