NASA's Land Processes Distributed Active Archive Center (LP DAAC) released the NASA Shuttle Radar Topography Mission (SRTM) collection on November 20, 2013. SRTM was the primary payload on the STS-99 mission of the Space Shuttle Endeavour, which launched February 11, 2000, and flew for 11 days.
NASA SRTM V3.0 has eliminated all voids with fill primarily from ASTER GDEM2 (Global Digital Elevation Model Version 2), and secondarily from USGS GMTED2010 - or USGS National Elevation Dataset (NED) for the United States (except Alaska) and northernmost Mexico.
NASA SRTM V3.0 data are distributed in two detail levels: NASA SRTM1 with one-arc-second postings for the U.S. and its Territories, and NASA SRTM3 sampled or averaged to three-arc-second postings for the world.
Check out the full product descriptions.
NASA Shuttle Radar Topography Mission United States 1 arc second - SRTMUS1
NASA Shuttle Radar Topography Mission United States 1 arc second number - SRTMUS1N
NASA Shuttle Radar Topography Mission Global 3 arc second - SRTMGL3
NASA Shuttle Radar Topography Mission Global 3 arc second number - SRTMGL3N
NASA Shuttle Radar Topography Mission Global 3 arc second sub-sampled - SRTMGLS