A portal is a layout object in one table where you place one or more related fields to display in rows the data from one or more related records.
The results of summary fields, calculations, and find requests are based on the full set of related records, not just the records in a portal that are filtered. For example, if a portal is displaying a filtered subset of records, and there is a total of summary field outside the portal summarizing these records. The summary field will total all related records, not just the displayed records.
Beginning with the portal, you can add a filter to a portal to specify the related records that are shown. Then you can easily define additional criteria for limiting the related records shown in a portal. By filtering records, you can display different sets of records in a portal. The results of a calculation that is used to filter records in a portal must have a Boolean result. Non-zero values are true, zero and empty values are false.