How does the program work when the inline keyword is not used in function code?

If in Kotlin (Android) you do not use the inline keyword for functions, then calling such a function results in a normal method call, which means:

• The function call goes through the call stack, which may add slight overhead.
• If the function contains lambda expressions, they may create objects and closures, affecting performance.

Using inline causes the compiler to substitute the function body directly at the call site, which:

• Eliminates call overhead.
• Allows optimizing lambdas by avoiding additional object creation.

Thus, without inline, functions work like regular methods, which is usually fine, but in performance-critical places or with frequent lambda use, consider inline for optimization.