A repeater is a way of displaying and customising the style of rows of table data, i.e. rather than using a table control, which renders the data in a grid layout.
The layout and style you choose is automatically applied to each row in the table.
You can also nest repeaters for more complex layouts, e.g. to show order lines within orders.
Because repeater rows are essentially custom formatted table rows, the Current row concept applies here too. For example, adding a button within a repeater row will cause the table row that it represents to become the current row.