What is ephemera?
Ephemera is a term for printed material originally intended to have a limited life-span, such as programmes, posters, tickets, flyers, and cards. These items were originally produced to pass on details about specific issues, activities, events, products, and services.

Why collect ephemera?
Libraries collect ephemera because it enhances information found in longer-lasting documents to give us a more “complete picture of life at a given point in time“. Some of this “throwaway" material has considerable visual appeal because it often combines text with images and photographs.

from the Auckland City Libraries website:
http://www.aucklandcitylibraries.com/aboutthelibraries/collections/Special-Collections/ephemera.aspx