A tensor is a multidimensional array that represents a generalization of vectors and matrices. It is one of the key data structures used in deep learning. Tensors are represented as n-dimensional arrays of base data types. The data type of each element in the Tensor is the same, and the data type is always known. It's possible that only a portion of the shape (that is, the number of dimensions and the size of each dimension) is known. Most operations yield fully-known tensors if their inputs are likewise fully known, however, in other circumstances, the shape of a tensor can only be determined at graph execution time.