The human genome reference assembly released in 2013 was GRCh38. It replaced GRCh37 as the primary reference framework used to organize, compare, and analyze human DNA sequences.
GRCh38 was produced by the Genome Reference Consortium and is also known as hg38 in the UCSC Genome Browser. It improved the reference by correcting errors, adding sequence, and resolving or reducing gaps that had remained in earlier assemblies. Its release date is commonly given as December 2013.
The names in this area are easy to mix up. GRCh37 was released in 2009, while NCBI Build 36 appeared in 2006 and NCBI Build 35 in 2004. GRCh38 is an assembly version, not the genome of one individual: it is a carefully constructed reference coordinate system used to map and describe variation across many human genomes.