Primary name column
By default, every table contains a Primary name column that is used to reference the table row within the user interface. Typically, the Primary Name column stores the name description of the data that is stored in a table's row and is a single line of text column. The Primary name column is the first column that is listed and available so you have a way to identify a record in a table.
You can see the Primary name column in various places in a model-driven app such within lookup columns, the header of a row form, and in the window title of the browser.
The Primary name column isn't the same as the uniqueidentifier key column that is also autogenerated when you create a new custom table. The Primary key column is a GUID.
You can update the schema name and display name of the Primary name until you create the table. After the table is created, you can't update the schema name. You can change the name of the Primary name column to make it friendlier for business users.
After creating a table, you can edit the Primary Name column and change its data type, choosing between a plain text column or an autogenerated string.
Tip
If you want to make the primary column unique, then create an alternate key and assign the Primary Name column to the new key.