Why would you get married kinda young?

Ellie • 18, Just keeping track of what`s happening down there ...
Ok, so I am still super young and new on this app and something that stoke me was the super high number of young women who got married and are trying to have kids ! Don't get me wrong, it's not like I am having an opinion on them or saying its bad decision, I can't and I don't because I don't understand it. 
 I am just curious about all those girls who get married VERY young like 18-24. I want to understand why because I feel like it is interesting to see someone my age with such a different life and perspective of life itself so why? 
Love obviously, but why the rush ? Why did you want to do something that could have waited until you are more of an adult ? Don't you feel like you are a bit young to decide this whole part of your life ?
I really don't understand, so if you have a minute to satisfy my never ending curiosity thank you !!