Almost every flag in the extensive collection of world flags is recognizable as rectangular. But among all the nations, there are two exceptions—nations with perfect squares for their official flags.

Test how well you really know world flags with this fun and challenging geography quiz.

London (CNN) — In the United States, the Stars and Stripes are everywhere: on porches, lawns and pickup trucks. The national flag is part of the scenery, almost invisible in its ubiquity. In England, ...