The dots and lines in Design View which help you position the controls.
A set of records that share a value or whose values fall within a certain range.
Group By
A query will group the values of fields with Group By in the Total row and then calculate the "total".
Group Header/Footer
The header for a group in a report appears just before the records for the group. The group footer appears after the last record in the group. (See Report Header/Footer for illustration)