From their webpage:
Ensembl is a joint project between EMBL - EBI and the Sanger Centre to develop a software system which produces and maintains automatic annotation on eukaryotic genomes. Ensembl is primarily funded by the Wellcome Trust.
With Ensembl you can ...
- Download all data, free, without constraints
- Search the DNA from the human genome
- Browse chromosomes
- Find genes, SNPs and mouse genome matches
- Look for proteins and protein families
Located at http://www.emsembl.org, Ensemble is one of a few public databases for the mapping of the human genome. Through their web interface, or programming libraries, a person may search the database for DNA sequence alignments via the BLAST search engine. BLAST allows you to look for a specific sequence in the entire database of the human (and mouse, to be accurate) genome.
Ensembl is a public domain repository that offers its service for free. Many private companies (such as GlaxoSmithKline) contribute their result data from their SNP research directly to them.