"Teachers need not even be familiar with the entire TPACK framework as such in order to benefit from it: they simply need to understand that instructional practices are best shaped by content-driven, pedagogically-sound, and technologically-forward thinking knowledge." - unknown
TPACK is a combination of three large knowledge bases, technological, content, and pedagogical. If you think of each of these as primary colors you know that when they cross over then more colors or in this case knowledge bases would be made. These combinations are:
Technological + Content = TCK
Pedagogical + Content = PCK
Technological + Pedagogical = TPK
When you look at all three cross over sections it is TPACK which for me is the ability to create appropriate pedagogical approaches to content with help of technological skills as a way to enhance the learning.