Understanding the Search Results

Mixed bag of data. In Entrez Nucleotides, for example, search results can include:

• archival data from GenBank/EMBL/DDBJ
• complete & characterized sequences
• sequence fragments (e.g., ESTs, GSSs)
• long genomic regions that are finished or in progress (high throughput genome sequences, HTGs)
• sequences of different molecule tpes (e.g., DNA, mRNA)
• Accession number distribution
• curated sequence records (RefSeq)
• sequence records drawn from PDB structure records

This is analagous to what you get with a novice PubMed search that retrieves various types of articles, ranging from case studies to randomized controlled trials, reviews, and meta-analyses. As is true for PubMed users, molecular database users might want to retrieve only certain types of records, and the Limits pages of those databases provide an idea of some commonly desired subsets.