LibcURL is a library for copying and downloading a file from an external url. This is very useful if you want to fetch a file from the web via a remote, text only system.
You can use curl to download a file from the web easily from the shell. Lets fetch a file from the matplotlib python examples
curl -LO http://matplotlib.org/examples/animation/basic_example.py
Note that the option -o is needed to save the file to your system.
There are many other commands which are supported by LibcURL, all of which can be found in the man pages (man curl).