The data editor dialog box can be found under the data menu or by clicking on its icon in the toolbar.

Existing datasets can be edited directly and new datasets created here. Select multiple datasets (in 1.18+) to edit simultaneously.

Enter new data on the row with the + sign to the left. Right click to insert rows anywhere or delete rows.

Data can also be copied to the clipboard by selecting the data to copy in the right panel, right clicking and choosing copy.

Tags

Existing datasets can get grouped and organized by creating "tags" and assigning them to a dataset.