Workflow describes business processes as the coordinated execution of simple activities (tasks) by human or automatic executors (agents). It also described as software systems that support the automatic execution of workflows.
Workflow is concerned with the automation of procedures where documents, information or tasks are passed between participants according to a defined set of rules to achieve business goal.
Workflow may be manually organized. In practice most workflow is normally organized within the context of an Information Technology system (IT System) to provide computerized support for the procedural automation.
Workflow can be automated using Workflow Management System.  A workflow management system automates processes by managing jobs and resources.  The Workflow Management Coalition describes Workflow management system (WfMS) as a system that defines, creates, and manages the execution of workflows through the use of software.  This software runs on one or more workflow engines, which are able to interpret the process definition, interact with workflow participants and IT tools and applications.
At the highest level, all WfMS may be characterized as providing support in three functional areas:

• The Build-time functions, concerned with defining and modeling the workflow process and its activities
• The Run-time control functions concerned with managing the workflow processes in an operational environment.
• The Run-time interactions with human users and IT application tools for processing the various activity steps.
  

This figure illustrates the basic characteristics of WfMS and the relationships between these main functions.

Many benefits can be gained by adopting WfMS in business. With the automated WfMS:

• Work doesn’t get misplaced; auditors are rarely required to recover from errors or mismanagement of the work.
• The managers can focus on staff and business issues, such as individual performance, optimal procedures, and special cases, rather than the routine assignment of tasks.
• The procedures are formally documented and followed exactly, ensuring that the work is performed in the way planned by management, meeting all business and regulatory requirements.
• The best person (or machine) is assigned to do each case, and the most important cases are assigned first. Users don’t waste time choosing which item to work on.
• Parallel processing, where two or more tasks are performed concurrently, is far more practical than in a traditional, manual workflow.

Enterprise Resource Planning (ERP) is an integrated information system that serves all departments within an enterprise.  ERP system aims to automate the business of an organization. It may integrate with other systems to achieve business goal.
The following Figure shows an example of ERP systems that attempts to cover all basic functions of an organization.

ERP Systems contain “embedded” business process knowledge.  However, these Systems are not able to represent (parameterized) business processes explicitly.  WfMSs are often positioned to solve this problem of business process management.
ERP system can use workflow management system to manage workflows inside its modules and between different ERP modules.

A workflow system can be described as a cube with three dimensions: Organization, Business process, and information, as shown in the following Figure.

Workflow system three dimensions

Organization contains the organization structure, the Employees that execute tasks and their position in the organization, and the roles of each employee in the organization. Roles are used to authorize a given employee to perform a specific task.
Information contains the information needed to perform process activities; this includes the application form and any supporting documents.
Business Process contains the structure of the business process; it describes the behavioral aspect of a workflow specification, from its initial state to one of its final states.

Business Process can be defined as a set of one or more linked procedures or activities which collectively realize a business objective or policy goal, normally within the context of an organizational structure defining functional roles and relationships.
Business process must be represented in a form of "Process Definition" to support automated manipulation.  The process definition consists of a network of activities and their relationships, criteria to indicate the start and termination of the process, and information about the individual activities.
When WfMS executes process, it creates an executable instance of the process called jobs.  Process contains all possibilities of the execution procedure while job shows the path that was truly passed while process execution.
Process consists of: Activities, Transitions, and Routing Points.  The following are the description of those components.

Activity defines the current work to be done by executer in the flow. There are two main types of activities; Automated Activity and Manual Activity.

• Automated Activity is an activity that can be executed by computer without human intervention such as email send or printing document. Also it can be a web service call to another system.
• Manual Activity is an activity that needs user intervention to accomplish it.

The following is the main attributes of Manual Activity:

• Activity Name: is a unique name for the activity in the process. It should be a friendly name describes the work to be done by this activity.
• Organization Roles: A mechanism to associate participants to a collection of workflow activities. The user that will work on the activity must be member to one of its roles.
• Deadline: is the duration allowed for this activity to finish. Activity executer (User) must finish working on the activity during this time. If the user didn’t finish work during the allowed time frame. A decision must be made:

• The activity may be forced to finished by the engine and the engine picks the next activity for execution
• The engine waits for the activity to finish and notify for late
• Or the engine may rout the activity for another user to accomplish it.

A point during the execution of a process instance where one activity completes and the thread of control passes to another, which starts.  A transition may be unconditional, such that completion of one activity always leads to the start of another.  Or it may be conditional, where the sequence of operation depends upon one or more Transition Conditions.  Transition Condition is a logical expression to be evaluated by a workflow engine to decide the sequence of activity execution within a process.

Routing point is an exit point of activity where engine must decide to rout to one or more next activates.  There are two types of routing, Parallel Routing and Sequential Routing.
The following Figure shows an example of process; a process called "Customer Support Process".

Example of a workflow process