In order to use a package, it needs to be installed on your computer by running install.packages('name_of_package') (do not forget '' around the name of the package, otherwise R will look for an object saved under that name!). R is open source so everyone can write code and publish it as a package, and everyone can install a package and start using the functions or datasets built inside the package, all this for free.
They extend existing base R functionalities by adding new ones. These extensions which are are collections of functions and datasets developed and published by R users are called packages.
You will thus often need to install some “extensions” to perform the analyses you want. Unlike other programs, only fundamental functionalities come by default with R.
