In this chapter, we have explored some of the functions of the lattice package. We have seen how easy it is to plot data as a function of groups. We have described some of the customization possibilities of lattice graphs. Through the example of the USCancerRates dataset, we have discussed the importance of data integration, which is merging data from several sources in order to build knowledge. In the process of exploring the functions of lattice, we have made some fascinating discoveries. In the next chapter, we will discover unsupervised clustering with kmeans().