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title: "AsyncBase::Start Method | Microsoft Docs"
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---
# AsyncBase::Start Method
Starts the asynchronous operation.  
  
## Syntax  
  
```  
STDMETHOD(  
   Start  
)(void);  
```  
  
## Return Value  
 S_OK if the operation starts or is already started; otherwise, E_ILLEGAL_STATE_CHANGE.  
  
## Remarks  
 Start() is a default implementation of IAsyncInfo::Start, and does no actual work. To actually start an asynchronous operation, override the OnStart() pure virtual method.  
  
## Requirements  
 **Header:** async.h  
  
 **Namespace:** Microsoft::WRL  
  
## See Also  
 [AsyncBase Class](../windows/asyncbase-class.md)