Important Key points Batch Process API in Drupal 7. Details about batch parameter like operations, finished, title, init_message, progress_message, error_message, file and $context variable.
Drupal Batch API
Example that utilizes the Batch API for Drupal 7, In this example we write users data on CSV file with batch process and download it.
Batch process in Drupal 7 is the execution of a series of programs. The Batch process spread out our series of programes over several page requests, thus ensuring that the processing does not get interrupted because of a PHP timeout.