A General Feature Format (GFF) file is a simple tab-delimited text file for describing genomic features. There are several slightly but significantly different GFF file formats. IGV supports the GFF2, GFF3 and GTF file formats.
One-based index: Start and end positions are identified using a one-based index. The end position is included. For example, setting start-end to 1-2 describes two bases, the first and second in the sequence.
Display settings: To modify IGV's default display settings for the .gff or .gff3 data, include a track line in the file.
Coloring features: To specify a color for a given feature, you can add this to the file as shown in the following example. Color values can be in either hexadecimal or RGB (r, g, b) format.