A portal is a layout object that displays a list of records, one record in each row. Use a portal only when you want to display data from more than one record.
A portal can display records from a related table or the current table. To add a portal that shows records from a related table:
•create a relationship with another table occurrence, then create a portal to display related records from that table occurrence; see Creating portals to display related records
•add an Add-on Table to your custom app; see Adding Add-on Tables to custom apps
You can also use a portal to list records from the current table next to details about that record in a master-detail layout. See Creating portals for master-detail layouts.