question

I'd say Event Handlars in SSIS are there to perform certain tasks when an event occurs - like logging execution status. As an example: If you have a package which performs a number of tasks, and you want to log the execution of each task to a Sql table, you probably don't want to flood your package with Execute SQL tasks. Instead, you could add an OnPostExecute event handler for the executables you want to log completion of. Also, you might want to continue to the next task in a control flow even if the preceeding task failed. Then you'd add an OnError event handler for the executable to handle the error but still keep going to the next task in the control flow.