When a program calls a synchronous function, the program halts and waits for the function to finish executing. When a program calls an asynchronous function, the program does not wait and continues to execute while the asynchronous function executes in the background.

By default, C# methods are synchronous. External functions that can take a long time to execute–such as interprocess communications (IPC) and database queries–are typically asynchronous. However, there may be instances where you need to make a synchronous function asynchronous and vice-versa.

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