Ooopsie, sorry, and thank you for looking up the CPL term
It originally starter with film cameras, and Linear Polarizer Filter was invented. In today's DSLR, Circular Ploarizer filters are used, due to design of digital sensors (Autofocus performance and overall metering).
CPL can essentially be use on any digital camera that has a thread on the front of the lens (so this would apply to DSLR, micro 4/3rds systems and many advanced Point and Shoot cameras).
It is as simple as mounting it to a front thread of the lens (in this case, just a cheap, plastic Holga lens if anyone remembers them) :
And while rotating the front element of CPL, you able to achieve the result that pleases you (removing unwanted reflections from non-metallic surfaces, like water or glass, enhancing the appearance of the clods and so on)
Personally, If you enjoy photography, and have a lens with threaded front element, I'd recommend having CPL to everyone, it is a great tool! Use it every time - no, but there are many situations, specially as Jal photo, as well as fall colors, you will love what it will help you to achieve!
P.S. If there is enough interest, maybe there is a place in the "Non-Gardening Related Hoo-ha and Foo
" section to have as sticky for photographic tips and trick that we can all share and contribute to?