What is Cache invalidation in Laravel, and what role does it play in a real application?

What is Cache invalidation in Laravel, and what role does it play in a real application? In Laravel, cache invalidation should be understood as part of a larger application architecture rather than as an isolated API call. Applications need a consistent strategy for removing or refreshing cache entries after source data changes. A strong understanding includes its purpose, the layer where it belongs, the data or request flow it affects, and the situations where another mechanism may be more appropriate. Practical context: Laravel caching stores reusable values in a configured cache store so expensive calculations or repeated data lookups do not have to run on every request. The specific focus here is cache invalidation: Applications need a consistent strategy for removing or refreshing cache entries after source data changes. This question is designed to test not only terminology, but also how the concept fits into Laravel's request, application, database, security, or deployment workflow.