This paper works well as an introduction to answer the question, "What is Darwin Core?" After an overview of the development of the Darwin Core Standard, and current examples of Darwin Core data in use, this paper goes on to describe current goals and challenges of integrating biodiversity data and what that means for Darwin Core.
From the Introduction section of the paper: "Darwin Core  is a standard for sharing data about biodiversity – the occurrence of life on earth and its associations with the environment. Darwin Core first emerged around 1999 as a loosely defined set of terms, and progressed through several iterations by different groups resulting in many different variants . A formal set of terms and processes to manage changes were necessary to ensure utility for data integration. These aspects were developed within the Darwin Core Task Group  of the Taxonomic Databases Working Group (TDWG; www.tdwg.org) and ratified as a standard in October 2009. The philosophy for Darwin Core development has been to keep the standard as simple and open as possible and to develop terms only when there is shared demand. Darwin Core has a relatively long history of community development and is deployed widely –. For example, the Global Biodiversity Information Facility currently indexes approximately 300 million Darwin Core-formatted records published by more than 340 organizations in 43 countries. Increasingly, Darwin Core is being incorporated in communities beyond that of natural history collections (Figure 1), in which the standard has its roots."