Why does installing numpy require python-dev in Kubuntu 12.04

Just starting out in python on a pendrive 12.04 Kubuntu environment. I had to install GCC (understand that), but I also had to install python-dev before I could use PIP to install numpy. Why do I need python-dev?

sudo apt-get install gcc
sudo apt-get install pip
cd /usr/lib/python2.7/
sudo apt-get install python-dev
sudo pip install numpy

Best answer

When you use pip to install numpy, the packages is compiled from source. The pythonx.x-dev packages contain the necessary header files for linking against python.