Question: What version of R do I run on my computer or laptop?
Answer: To get the information about the version of R, use the following command at R prompt.
> # get a version of R
You will get a result like
 “R version 3.2.1 (2015-06-18)”
Note that a package in R language is a collection of objects that R Language can use. A package contains functions, data set, and documentation (which helps how to use the package) or other objects such as dynamically loaded libraries of already compiled code.
Question: How to check what packages are already installed?
Answer: To get a list of installed packages in R, write “library()” without quotation marks at the R prompt. R will first list all of the packages installed in the local R directory of your computer system and then it will list all packages installed globally on your computer system.
# list all packages installed
You would get results like (note that results below are given as an example only, it’s not a complete list)
Packages in library ‘C:/Program Files/R/R-3.2.1/library’:
KernSmooth Functions for kernel smoothing for Wand & Jones (1995)
MASS Support Functions and Datasets for Venables and Ripley’s MASS
Matrix Sparse and Dense Matrix Classes and Methods
methods Formal Methods and Classes
mgcv Mixed GAM Computation Vehicle with Automatic
Following is a very short list of packages installed in the local library.
abind Combine Multidimensional Arrays
AlgDesign Algorithmic Experimental Design
askpass Safe Password Entry for R, Git, and SSH
assertthat Easy Pre and Post Assertions
tibble Simple Data Frames
plyr Tools for Splitting, Applying and Combining Data
For further detail on packages in R, see the link Packages in R Language.