Quite often data isn’t in a format that makes it readily available for both mapping software and people to read. Many data formats store the geographic data in a binary format. This format is normally readable only by computers and is designed for software to use. Some spatial data formats are in a simple text format, which is easier to explore.
One example of a text-based format is Geography Markup Language (GML). It uses a text syntax to encode coordinates into a text file. GML can then be read or manually edited without needing a special piece of software or at least nothing more than a common text editor. Creating GML from scratch isn’t very pleasant. Fortunately, another OGR utility exists that can convert OGR-supported data formats into and out of other formats, including GML.