How to: Make Columns Read-Only in the Windows Forms DataGridView Control Using the Designer
By default, users can modify text and numerical data displayed in the Windows Forms DataGridView control. If you want to display data that is not meant for modification, you must make the columns that contain the data read-only. For information about how to make the control entirely read-only, see How to: Prevent Row Addition and Deletion in the Windows Forms DataGridView Control Using the Designer.
The following procedure requires a Windows Application project with a form containing a DataGridView control. For information about setting up such a project, see How to: Create a New Windows Forms Application Project and How to: Add Controls to Windows Forms.
The dialog boxes and menu commands you see might differ from those described in Help depending on your active settings or edition. To change your settings, choose Import and Export Settings on the Tools menu. For more information, see Working with Settings.
To make a column read-only by using the designer
Click the smart tag glyph () on the upper-right corner of the DataGridView control, and then select Edit Columns.
Select a column from the Selected Columns list.
In the Column Properties grid, set the ReadOnly property to true.
You can also make a column read-only when you add it by selecting the Read Only check box in the Add Column dialog box.