So you know how every person is different and has their own unique way of being? Well, scientists study these different ways people are and they call it their "personality." One way they measure personality is by using something called the "neuroticism extraversion openness personality inventory" or NEO-PI-R for short (that's a big word!).
The NEO-PI-R helps scientists understand five different parts of a person's personality: One part is called "neuroticism" (which is a fancy word for how much someone worries or feels anxious). Another part is "extraversion," which is how much someone likes being around other people and being the center of attention. The third part is called "openness," which is how much someone likes trying new things and being creative.
The inventory is like a big test that asks a lot of questions about what a person thinks, feels, and wants. It's kind of like a game where people answer lots of questions about how they act and feel, and then scientists look at their answers to see what kind of personality they have. It helps them understand how different people see and experience the world in their own way.