The origin of galactic cosmic rays

Initial discovery of Cosmic Rays (CRs) dates back to a century ago (1912). Their identification as particles rather than radiation dates to about 20 years later and in 20 more years also the first suggestion that they were associated with SNRs was in place. The basic mechanism behind their acceleration was suggested almost 40 years ago. Much work has been done since then with regard to the aim of proving that both the acceleration mechanism and site are well-understood, but no definite proof has been obtained: in spite of impressive progress of both theory and observations, the evidence in support of the commonly accepted interpretation is only circumstantial. In the following, I will try to make the point on where we stand in terms of how our theories confront with data. I will review recent progress on the subject and try pointing the avenues to pursue in order to gather new proofs, if not a smoking gun evidence of the origin of Galactic CRs.