1. An Esri Shapefile (SHP) import requires the following three files in the same directory, with the same name and following extensions: .SHP which stores geometry, .DBF which contains the database attributes for the geometry and a .SHX which is the index to correlate the geometry to the attributes. In addition to these three required files, you can have more files with other extensions such as .PRJ which stores projection information.
2. A MIF (MapInfo Interchange Format) file import requires two files in the same directory, with the same name and following extensions: .MIF which stores geometry and .MID which stores database attributes for the geometry.
3. A GML import requires at least two files: the data file, typically named .GML or .XML, and the schema file, typically named .XSD. Version 2.1 and 3.1 of GML are supported.