Message: Thanks for an informative and interested podcast . I have learned R alone by reading in Internet, and being able to hear an actual voice is a refreshing experience. I'm catching up with the past podcasts and have completed only 3. However, I have a few questions y data structures. Some data aggregation functions return a Table class that I don't know how to use other than printing it. Therefore I have avoided them in favor of other functions like those in the plyr package. I have also read things about data.table, regarding it being a newer/better alternative to dataframe. Can you talk us about those two data structures? Thanks! Eric