Database indexes are an internal mechanism that can be used to increase the speed at which Access can find information in your database. You can apply an index to one or more of your database columns at this step. Simply click the "Indexed" pull-down menu and select the appropriate option.
Keep in mind that indexes create a lot of overhead for your database and will increase the amount of disk space used. For this reason, you want to keep indexed columns to a minimum. In our database, we'll most often be searching on the Last Name of our contacts, so let's create an index on this field. We might have friends with the same last name, so we do want to allow duplicates here. Ensure that the Last Name column is selected in the bottom potion of the windows and then select "Yes (Duplicates OK)" from the Indexed pull-down menu. Click Next to continue.