Throughout one's life, one's sense of "self" (using "self" to encompass emotional, social, ego, etc.) and one's character is constantly evolving. Consequently, a person's interaction with the outside world also changes. People refer to this evolution as "maturing". Throughout what is commonly called the "developmental years", we test our boundaries and take note of outcomes in a sort of experiment with the world. This is why teenagers get a bad rep - the teen years is when the bulk of the "boundary testing" happens. Indeed, "boundaries"are always being tested and life constantly provides new and different scenarios to learn from, so one never really ceases to mature. If learning would stop, maturing would stop, and one would merely "age".
Now, should traumatic experience(s) happen during the formulative years, these experiences can either stunt or accelerate a person's evolution depending on the circumstances. Some people are sheltered and only get "life exposure" in small amounts until later on. Others get too much "life exposure" too early and don't have the emotional capacity to process or cope with such exposure. When I say "life exposure", I'm generally speaking of experiences and inputs that everone has that forces the evolution: deaths, divorce, money, drugs/alcohol, responsibility, Military, graduation, employment, love, loss, religion.... life scenarios.
"Maturity" isn't a switch you flip and you have it, it's not in a crown royal bag stuffed under someone's dashboard for you to find. When one is said to be "mature", it's is meant that, in accordance with their age, they act and interact with their world appropriately. You've heard terms like "mature for one's age". This means that someone has displayed characteristics that an older and more evolved person would typically display. Character traits such as respect, diplomacy, responsibility, tolerance, fallibility and restraint typically don't develop until later years, some never develop these traits. When a person consistantly displays some of these traits early on they are seen as "mature for their age".
There really isn't a gauge to determine maturity. The dictionary only defines it as being ripe. By definition, you are "a mature human" once you can get someone/become pregnant. But we typically refer to someone who is socially and mentally fully functional as mature.
Here's something to help you:
Immature people call other people immature.
Mature people (Adults!) have other things to worry about/consider besides another person's maturity, or, a mature person would have had enough diplomacy/restraint/tolerance to not "call someone immature". Instead, an adult would have the foresight enough to avoid the confrontation and wherewithal to remove the irritation from their life.
I must give the
to this site for the fact that there is so much "experience" of others and information on here that normally may take many years to be exposed to. This site is really a maturity gold mine... but how much you dig determines how much gold you find.
