It is a file format (filename extension .sid) developed and patented[2][3] by LizardTech (in October 2018 absorbed into Extensis)[4] for encoding of georeferenced raster graphics, such as orthophotos.
According to the Open Source Geospatial Foundation (which releases GDAL), MrSID was developed "under the aegis of the U.S. government for storing fingerprints for the FBI.
Moreover, MrSID holds promise for being used in image compression and editing for desktop publishing and nonlinear digital video software.
Most commercial GIS software packages can read some versions of MrSID files including those from GE Smallworld, ESRI, Intergraph, Bentley Systems, MapInfo, Safe Software, Autodesk, with ERDAS IMAGINE being able to both read and write MrSID files.
Some image editing and management software systems can also read MrSID files, including XnView and IrfanView.