In ArcGIS, how do I add a field to a dataset or table?

To add a field to a dataset or table in ArcGIS, use one of the following procedures:

Adding a field in ArcMap

1. In ArcMap's Table of Contents, right-click the desired data layer, and then select Open Attribute Table.
   
   
2. From the Table Options menu, select Add field. If the Add field button is grayed out, make sure you are not in an editing session.
   
   
3. In the Add Field window, set the parameters of the new field.

   Note: You cannot change the parameters once you add the new field. For more about data types, see Esri Help's ArcGIS field data types.

Adding a field in ArcCatalog

Note: Close your table or dataset in ArcMap before adding a field in ArcCatalog, or a sharing violation may prevent you from adding the field.

1. On the left, in the catalog tree, select the folder where the dataset is located.
   
   
2. On the right, from the catalog view, right-click the dataset or table, and then select Properties.
   
   
3. Select the Fields tab.
   
   
4. At the bottom of the "Field Name" column, type the name of your new field in the blank text box.
   
   
5. In the "Data Type" field, use the drop-down list to select the data type.

   Note: You cannot change the parameters once you add the new field. For more, see Esri Help's ArcGIS field data types.

6. When you are finished adding fields, click OK.

Adding a field to a coverage in ArcCatalog

1. Open a coverage in ArcCatalog, and then open the appropriate folder feature type (e.g., polygon, point, arc, or label). The Coverage Feature Class Properties window will appear.
   
   
2. To add a field, under the Items tab, click Add.
   
   
3. If the Add button is grayed out, click any item in the table to activate it. If the Add button stays grayed out, verify that you are working with an ArcInfo license. This license is necessary for coverage editing in ArcGIS Desktop.
   
   
4. When you are finished adding fields, click OK.