A source is a type of feature (functional group) that conveys information about the biological source(s) of the specified span of the sequence, and allows a submitter to annotate information about those biological source(s) to the sequence record.

Every sequence submission should have either a single source annotated to it that spans the entire sequence or multiple sources annotated to it, which together, span the entire sequence.

For more information on the “source” feature type, please see the alphabetic list of Feature types in section 3.2 of the DDBJ/EMBL/GenBank Feature Table definition document. The entry for “source” will provide a list of modifiers (qualifiers) that can be used with the “source” feature type.