If the dataset that you added to ArcMap has geographic coordinates, the units will still display as ‘Decimal Degrees’ or in Degrees, Minutes and Seconds (DMS) (e.g. 82°45’46.8″E 41°44’56.4″N) even though the datum has yet to be defined. This is because latitude and longitude values always have angular units. Defining a geographic or projected coordinate system for a shapefile, Esri Grid format, raster dataset (TIFF, JPG) or a file geodatabase does not require you to output to a new dataset. The Define Projection tool updates your existing dataset by creating an associated file (e.g. .prj, prj.adf,.aux). For personal geodatabases, the spatial reference table is updated. After specifying the location and name for the new projected data, specify the output coordinate system to project the data. If it is required, select an optional geographic transformation and complete the projection! I want to transform a shapefile from WGS84(Geographic) to European Albers Equal Area Conical projection. What are the 7 parameters? Kindly help me There’s isn’t a continent-wide 7 parameter transformation between ED 1950 and WGS 1984. I would use ED_1950_To_WGS_1984_1. If your area of interest is smaller, check the geographic_transformations.pdf file in the ArcGIS installation’s Documentation folder for possibilities. Alternatively, you could modify the Europe Albers definition and use a different geographic coordinate system like ETRS 1989 or WGS 1984. Source.