InDesign Articles panel’s main purpose is easier ePub creation. It allows you to control the output order of document items when exporting to ePub, HTML, or tagged PDF.

After opening the Articles panel, drag the items you want to export into the panel. You can drag items one at a time, as a group, or Command+click/Ctrl+click the Add button to add every item in a document. Dragging in smaller selections allows you to create individual articles from your selection that you can then choose to export or not. You can choose to exclude entire articles from export, and you can drag to re-arrange item export order of entire articles or individual items within articles. Anything that isn’t in the Articles panel—or unchecked in the panel—when exporting based on the Articles panel won’t be exported.