NCEI provides distributed data access via the Open source Project for a Network Data Access Protocol (OPeNDAP) compliant THREDDS and ERDDAP data servers. OPeNDAP is a binary-level protocol that delivers subsetted data to a wide variety of platforms from gridded datasets on demand. This process is more efficient than downloading entire files via FTP or HTTP because OPeNDAP responses only deliver the dimensions, variables, and ranges being requested. Many OPeNDAP-compliant applications and libraries are available to interface with NCEI servers, including ToolsUI, IDV, Panoply, and NetCDF libraries for Java, Matlab, Octave, and Python.