reliance
Dependence on someone or something you seriously count on.
Reliance means depending on someone or something, trusting that they'll come through when you need them. When you have reliance on your alarm clock, you count on it to wake you up for school. When a team has reliance on its best player, they trust her to perform well in important games.
The word suggests more than casual trust. It means you're counting on that person or thing in a serious way. A hiker in the wilderness has reliance on her map and compass to find the way home. A small business might have too much reliance on a single customer, which means trouble if that customer leaves.
You can be reliant on something (the adjective form), or you can place your reliance in it (the noun form). A baby is completely reliant on their parents for food and care. As children grow older, they become less reliant on adults and develop self-reliance, meaning they can depend on themselves.
Reliance isn't always wise. If you place too much reliance on one study method, you might struggle when it doesn't work. People often spread their reliance around, like a cyclist who checks their brakes, tires, and lights before a long ride, rather than assuming one part will keep them safe.