A flag is a box with two colors blended together. It is roughly equivalent to a website's favicon 
.
You can hover over a flag to see information about the wiki it represents. You can also click on it with various effects.
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Title Flag
A flag at the top of a page, near a title, represents the wiki that hosts the page. If you hover, it shows the hostname (such as `faq.wiki.oddly-influenced.dev`). If you click on it, it discards the Attention Neighborhood and sets the Origin to the represented wiki.