Ephemera used to refer to printed matter but I would include film, audio and internet on top of that. Like a mayfly, most pieces of brand communications are not intended to endure for any length of time, however long-lived the brand behind them may be.
But it's good that there are people devoted to keeping such ephemera alive. One place I really must get round to seeing next time I'm in London is the Museum of Brands, housing the collection started by Robert Opie. Because even though the posters, wrappers, packs and print ads of my past have long exited into the great recycling machine in the sky, the impressions that they made have left permanent traces in my mind.