A table can be added to an article or story by clicking the table icon in the text editor's toolbar.

This will trigger the table editor from which you'll be able to add or remove columns/rows and format the table's content:

If you'd like to edit an existing table, simply select it from the text editor. It will appear as an attachment, much like images, files and videos, and clicking the table icon when a table is selected will open the editor for that table.

All tables created will be mobile friendly by being scrollable horizontally if they're too large.