On the Last Run

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This is a "sidebar", and the sidebar contains "Widgets" - pretty weird name, right.

This particular sidebar is called your "Primary Sidebar" and appears on your blog pages posts.

"Widgets" within sidebars allow you to add arbitrary content to your website in pre-defined areas ("sidebars" as mentioned above).

You can edit these Widgets in:

Dashboard > Design > Customize

or

Dashboard > Design > Widgets

and there's a great video about "Widgets" in the Knowledgebase.