The human genome is the genome of Homo sapiens, which is composed of 24 distinct chromosomes (22 autosomal + X + Y) with a total of approximately 3 billion DNA base pairs containing an estimated 20,000�25,000 genes. The Human Genome Project has produced a reference sequence of the euchromatic human genome, which is used worldwide in biomedical sciences. The human genome is much more gene-sparse than was initially predicted at the outset of the Human Genome Project, with only about 1.5% of the total length serving as protein-coding exons, with the rest of the genome comprised by RNA genes, regulatory sequences, introns and controversely so-called junk DNA.
The Human Genome Project (HGP) is a project undertaken in 1990. The goal of the HGP was to understand the genetic makeup of the human species by identifying all the genes in the human genome and mapping how individual genes are sequenced. By some definitions the HGP was completed in 2005.