In bioinformatics, the general feature format (gene-finding format, generic feature format, GFF) is a file format used for describing genes and other features of DNA, RNA and protein sequences.

The following versions of GFF exist:

• General Feature Format Version 2, generally deprecated
  • Gene Transfer Format 2.2, a derivative used by Ensembl
• Generic Feature Format Version 3
  • Genome Variation Format, with additional pragmas and attributes for sequence_alteration features

GFF2/GTF had a number of deficiencies, notably that it can only represent two-level feature hierarchies and thus cannot handle the three-level hierarchy of gene → transcript → exon. GFF3 addresses this and other deficiencies. For example, it supports arbitrarily many hierarchical levels, and gives specific meanings to certain tags in the attributes field.

The GTF is identical to GFF, version 2.^[1]

All GFF formats (GFF2, GFF3 and GTF) are tab delimited with 9 fields per line. They all share the same structure for the first 7 fields, while differing in the content and format of the ninth field. Some field names have been changed in GFF3 to avoid confusion. For example, the "seqid" field was formerly referred to as "sequence", which may be confused with a nucleotide or amino acid chain. The general structure is as follows:

• Distributed Annotation System
• Variant Call Format
• Sequence alignment