It has become a requirement of publication to make the data generated for publication, publicly available. There are several genomic data repositories for data deposition. These data are processed, compiled, and made accessible via genome browsers. Omics experiments often rely heavily on available data as a starting point. Sometimes it may even be possible to make use of existing data rather than needing to generate new data. The first step in any Omics experiment is therefore to check what data are available.
 
The two primary genomics databases are the NCBI Genome Database and the Ensemble Genome Database. These databases contain genomes across all kingdoms of organisms. Most of the sequences, though are focused on model organisms. There are already thousands of organisms for which we have genomic sequences, as well as thousands of human genomes. There are also several databases for specific purposes like the cancer genome databases, that focus on genomes of a variety of cancers.