Why does the world have borders

HI people of the planet it is me again writing on a response of why does the world have borders and well my believes are that the world has borders because other countries want a literal expression of the line. by that I am referring to the line that separates one country from another. This is true because there are many borders around the world like in Canada, Mexico, and the U.S. Besides serving as boundary of countries borders also keep people in and out of a country. Usually one of the countries that has a border makes up the rules on how to cross it like Visa cards or money. But a bigger reason may be because to many people cross over or take or something I actually at this point am not sure ... Oh well I will end this post right now oh and by the way the reason on why I capitalized hi is because I am in a pretty good mood OK bye.