key to
prep. phr..prep. phr.. the main thing that leads to something or makes it possible — often used for solutions, secrets, or essential factors.
prep. phr.. introducing the essential element or solution to a problem, situation, or outcome; typically followed by a noun phrase indicating the result or goal.
The key to success is hard work.
The teacher explained that the key to solving the problem was understanding the basic principles.
In his speech, the economist emphasized that the key to long-term economic stability lies in sustainable resource management.
followed by a noun or noun phrase indicating the result, goal, or essential factor.
contrast with 'the secret to' (more mysterious) and 'the solution to' (more direct), which share the same prepositional structure but differ in connotation.