« on: 06/10/2015 01:10:12 »
Hi Diogo, welcome.Thank you very much Bill!
Very briefly, dark matter was suggested as an explanation for things such as the speed of rotation of galaxies, which didn't seem quite "right".
Dark energy was proposed when it was discovered that the expansion of the Universe is accelerating. Something had to be "pushing" it.
It might be worth keeping an eye on the thread "The nature of dark matter"; the chances are some of your questions will be answered there, and that will avoid repetition. If not; keep asking; our experts sometimes need prodding.