It is well established that hydrogen and most helium were created during the Big Bang, together with few isotopes and light elements, while heavier elements ("metals") were formed by nucleosynthesis in stellar interiors or during stellar explosions. It is also well established, that galaxies have been gradually enriched in those elements. This is unambiguously indicated by the chemical abundances observed both in stars and in the interstellar medium. Far less understood are the properties of the many steps of the long journey accomplished by newly produced nuclei until they reach the places where we see them now.

How long do the nuclei ejected by supernovae stay in a very hot and tenuous phase, visible only with X-ray telescopes?

Do they rather stay within their parent galaxies, or do they escape into in the intergalactic medium, progressively enriching it?

Do they travel from one galaxy to another?

Is the dispersal of elements a purely galactic process or does it work also at intergalactic scales?

How does the matter lost in stellar winds finally becomes part of the interstellar medium?

Are metal-rich pockets produced in the interstellar medium? How large and long lived would these metal-rich pockets be and what would be their physical status and composition?

By what mechanisms would they be destroyed, until complete small-scale mixing of fresh elements into the preexisting interstellar medium?

Do the nuclei pass a long time imprisoned in dust grains or molecules, before finding themselves again "naked" in the stellar interiors, and prone to be transformed into another species in the stellar factories?

Do most of them - or a fraction - end up in the form of so-called dark matter, yet invisible but known to be there?

Such are questions, among many others, that one asks oneself and to which Science has no definite answer so far. The purpose of this meeting is to gather researchers in all fields of astronomy, observational and theoretical, who are interested by these questions and can help providing new clues.