When you're vulnerable, you're in a position where you could easily be hurt, damaged, or attacked. A turtle without its shell would be vulnerable to predators. A castle without walls would be vulnerable to enemy armies. When you share something personal that matters deeply to you, like a secret fear or a dream you're nervous about, you make yourself vulnerable because someone could use that information to hurt your feelings.

Being vulnerable isn't always bad, though. Sometimes opening up and being vulnerable with people you trust actually makes friendships stronger. When you admit you don't understand something in class, you're being vulnerable, but it lets the teacher help you learn. Athletes are vulnerable to injury, which is why they wear protective equipment.

You might hear about vulnerable computer systems that hackers could break into, or vulnerable neighborhoods at risk during hurricanes. Animals can be vulnerable to extinction when their habitats disappear. A soccer goalie who runs too far from the net leaves the goal vulnerable.

Vulnerability (the noun form) describes this state of openness to harm. Understanding when you're vulnerable, and when it's worth being vulnerable anyway, is part of growing up and making good decisions about trust and risk.