dplyr: a grammar of data manipulation
dplyr provides a flexible grammar of data manipulation. It's the next iteration of plyr, focused on tools for working with data frames (hence the d in the name).
It has three main goals:
Identify the most important data manipulation verbs and make them easy to use from R.
Provide blazing fast performance for in-memory data by writing key pieces in C++ (using Rcpp)
Use the same interface to work with data no matter where it's stored, whether in a data frame, a data table or database.
To learn more about dplyr, start with the vignettes:
browseVignettes(package = "dplyr")