In statistics, data can initially be considered to be one of three basic types: categorical, discrete numeric, and continuous numeric. Methods for viewing and summarizing data depend on which type it is, so we need to be aware of how each is handled and what we can do with it. In this chapter we look at graphical and numeric summaries of a data set for a single variable. The graphical summaries allow us to grasp qualitative aspects of a data set immediately. Numerical summaries allow us to compare values for the sample with parameters for a population. These comparisons will be the subject of the second half of this text.