A national flag is a flag that represents and symbolizes a country. Flags come in many shapes and designs, which often represent something about the country or people that the flag represents. Common design elements of flags include shapes such as stars, stripes, and crosses, layout elements such as including a canton (a rectangle with a distinct design, such as another national flag), and the overall shape of a flag, such as the aspect ratio of a rectangular flag (whether the flag is square or rectangle, and how wide it is) or the choice of a non-rectangular flag. Sometimes these flags are used to represent languages.
Many countries with shared history, culture, ethnicity, or religion have similarities in their flags that represent this connection. Sets of flags in this list within the same category may represent countries' shared connections, or the design similarity may be a coincidence.