ESRI shapefiles store geographic features and their attribute data in a simple, non-topological vector format. Each shapefile stores features belonging to a single feature class of point, line, or polygon.
A shapefile is actually a set of three constituent files with the same name and different extensions - *.shp, *.shx, and *.dbf. The *.shp file stores the feature geometry. The *.shx file stores the index of the feature geometry. The *.dbf file is a dBASE file that stores the attributes of the features. A shapefile can also include files that store projection or additional indexing information.
Use Catalog to add shapefiles to your map.
Layers corresponding to the data you added appear in the legend of your map.
Shapefiles cannot be drawn in ArcIMS and are not listed in Catalog when
Refresh Catalog by right-clicking on a folder and clicking Refresh.