A file with MPP extension is Microsoft Project data file that stores information related to project management in an integrated manner. It is proprietary file format developed by Microsoft as file format for Microsoft Project (MSP) which is a project management application software. Besides MPP, MSP supports other file formats as well like project XML schema. Several APIs and applications provide the facility to convert MPP file format to others. Find out more here about Microsoft Project File.
You can also view many other file formats. Please see the complete list below.