Filters and advanced filters allow you to work on certain filtered rows (records) of a data range. In the spreadsheets in LibreOffice there are various possibilities for applying filters.
One use for the AutoFilter function is to quickly restrict the display to records with identical entries in a data field.
In the Filter dialog, you can also define ranges which contain the values in particular data fields. You can use the standard filter to connect up to three conditions with either a logical AND or a logical OR operator.
The Advanced filter exceeds the three condition limitation and allows up to a total of eight filter conditions. With advanced filters you enter the conditions directly into the sheet.
To remove a filter, so that you see all cells again, click inside the area where the filter was applied, then choose.
When you select multiple rows from an area where a filter was applied, then this selection can include rows that are visible and rows that are hidden by the filter. If you then apply formatting, or delete the selected rows, this action then applies only to the visible rows. The hidden rows are not affected.
This is the opposite to rows that you have hidden manually by the Format - Rows - Hide Rows command. Manually hidden rows are deleted when you delete a selection that contains them.