MATLAB uses a variety of data types which were obtained by typing help class in the command line: double. This chapter focuses on two data types: cells and structures. Cells have advantages over matrices, and structures have advantages over cells. Cells allow for different numbers of elements in different rows, whereas matrices do not. Cells also allow for different types of data within them, whereas matrices do not. The problem arose because a matrix, which is delimited by straight brackets, cannot have different data types within it, such as double and char. By contrast, a cell, which is surrounded by curly braces, can have different data types. The structure is the most versatile data type for purposes. A structure can have fields of different kinds and numbers. One way to think of a structure is as a hierarchy of fields.