When you look at a certain national flag do you observe something? I know there are over 250 national flags out there but still you can have an opinion on what you had observed. Look at all the flags then observe the designs of the different flags from the color, shape of the flag, different shapes that are used in the flag, emblem, national symbol used, writings and other more.
Depending on what country some flags have their national symbol added to it like, for example, the coats of arms. Mostly all national flags are in rectangular form but they might not have the same measurement. The only flag that is not in a rectangular shape is the Nepal flag and the flag of the Vatican City and Switzerland are in the exact square.
Now we go with the colors that are used in a national flag. Do you observe something with all the national flags on the color that are most used or popular? Look all the national flag and list all the most used color that you observed. If you are done already listing the most used color that you saw at the different national flag, let compare notes if we have the same observation. In my list the most used or popular color for a national flag is the red where in around 155 flags used this, 144 flags used white, 102 flags used yellow, 97 flags used green, 69 flags used black, 68 flags used dark blue, 44 flags used light blue, 12 flags used light orange and also light brown, 10 flags used dark brown, 7 flags used grey and 6 flags used purple.
Also, in a flag, you might also observe that there are at least 3 colors that are used. The colors that are used have its own meaning on why they choose this color for their flag. Not all country have the same perspective of the colors that are used, each country has different interpretation with the colors.
Studying flags is not as boring as you think it is. There are a lot to learn especially on how the flag come out.