National Science Digital Library
The United States' National Science Digital Library (NSDL) is an open-access online digital library and collaborative network of disciplinary and grade-level focused education providers. NSDL's mission is to provide quality digital learning collections to the science, technology, engineering, and mathematics (STEM) education community, both formal and informal, institutional and individual. NSDL's collections are refined by a network of STEM educational and disciplinary professionals. Their work is based on user data, disciplinary knowledge, and participation in the evolution of digital resources as major elements of effective STEM learning. Resource types available via NSDL  include instructional materials, activities, lesson plans, audio/video materials, images, web sites, simulations, visualizations, tools, and services. NSDL also provides annotation collection and paradata (usage data) collections: comments, ratings, or usage information attached to existing resources in the NSDL. History. The National Science Digital Library (NSDL) was established in 2000 by the National Science Foundation (NSF) to provide an organized point of access to STEM content aggregated from a variety of other digital libraries, NSF-funded projects, and other national STEM stakeholder providers. Key collaborations with disciplinary communities and audience-focused providers grew out of the NSDL, providing a social  and technical infrastructure for collaboration in the delivery and use of digital resources in STEM education . NSDL also provides access to services and tools that enhance the use of this content in a variety of contexts. NSDL is designed primarily for K-16 educators, but anyone can access NSDL.org and search the library at no cost, and without creating a user account, although some content providers require a nominal fee or subscription to retrieve their specific resources. From 2000 – 2011, the National Science Foundation sponsored an NSDL grant-making program in the Division of Undergraduate Education (DUE) of the Education and  Human Resources Directorate. The National STEM Distributed Learning (NSDL) program offered grants to support major collection-building efforts, services development, and targeted research that built and extended library services. In February 2011, the NSF ended the NSDL grant-making program in DUE, and did not issue an NSDL program solicitation for FY2011. Originally a collaboration between Cornell University, Columbia University, and the University Corporation for Atmospheric Research (UCAR), the NSDL is now entirely hosted at UCAR, in Boulder, Colorado, and continues its mission as an entity dedicated to the advancement of STEM education.