Use unwrap for silent panics on unexpected errors and expect to provide custom error messages when a failure occurs.
Use unwrap when a failure is unexpected and crashing is acceptable; use expect when you need to provide a custom error message upon failure. Both methods panic if the Result or Option is an error or None, but expect allows you to define the panic message.
let file = File::open("hello.txt").expect("Failed to open hello.txt");
let value = Some(5).unwrap();
Both methods force a program to stop if something goes wrong, but they differ in how they report the problem. Use unwrap for simple cases where a failure shouldn't happen, and use expect when you want to tell the user exactly what went wrong. Think of unwrap as a silent alarm that just stops the machine, while expect is an alarm that also shouts a specific reason for stopping.