An existential crisis is when someone starts to question their life and the way they live it. For example, they might wonder why they are doing certain things, why they are living a certain way, or why they believe in certain things. It can be kind of like an identity crisis because they are doubting their purpose in life. Existential crises can be really hard and scary, but it is important to remember that it is okay to feel this way, and it's normal to think about this stuff.