Raku's `INIT` and `END` phasers manage program execution at runtime. `INIT` runs before the main program starts, executing queued code blocks in load order. It's ideal for setting up external resources like database connections. `END` executes after program termination, running cleanup tasks in reverse order. These phasers provide structured control over program lifecycle stages.

Unlike compile-time phasers like `BEGIN`, these handle runtime initialization and shutdown. They ensure reliable resource management, as Raku doesn't guarantee timely destruction via `DESTROY`. Developers use `INIT` for setup and `END` for orderly teardown, logging, or performance metrics. Code blocks can be scoped within subroutines or classes for localized control.

Practical uses include timing program execution and appending run logs. For example, `END say now - INIT now` reports total runtime. A database connection made in `INIT` can be safely disconnected in `END` using `with` guards. This pattern is vital for applications needing deterministic resource handling beyond language garbage collection.