SharePoint workflow refers to the automation of a business process by step by step execution of steps. In many cases the workflow instances have indeterminate delays and overall duration due to the necessity to interact with human users. This differentiates workflow from other means of automation such as Event Receivers. There are two types of workflows - Sequential Workflows - State Machine Workflow
Workflows help people to collaborate on documents and to manage project tasks by implementing business processes on documents and items in a SharePoint site.
Workflows help organizations to adhere to consistent business processes, and they also improve organizational efficiency and productivity by managing the tasks and steps involved in business processes. This enables the people who perform these tasks to concentrate on performing the work rather than managing the workflow.
References:
