Four important areas of real-time scheduling:
            1. Fixed-priority scheduling.
            2. Dynamic-priority scheduling.
            3. Soft real-time applications.
            4. Feedback scheduling.

Fixed-priority scheduling:
          Fixed priority scheduling is generally applied to tasks. A task, sometimes also called a process or thread, is a potentially infinite sequence of jobs. A task is periodic if it is time triggered, with a regular release. The length of the time between releases of successive jobs of task is a constant. Ti is called the period of the task.
         
Dynamic-priority scheduling:
          With dynamic-priority scheduling, task priorities are assigned to individual jobs. One of the most used algorithms belonging to this class is the Earliest Deadline First (EDF) algorithm, according to which priorities assigned to tasks absolute deadlines of the active job.
Soft real-time applications
          The soft real-time criterion opens up the possibility of having a predictable system with much higher levels of utilization than can be achieved under the hard real-time task formulation. Of course, this increased utilization level can be obtained only at the cost of either some missed deadlines or some jobs denied access to the system, or both.

Feedback scheduling
          Feedback is a powerful concept that has played a pivotal role in the development of many areas of engineering. It has several advantages. Feedback can make a system robust towards external and internal disturbances and uncertainties. Using feedback, it is possible to create linear behavior out of non-linear components and to modify the dynamic behavior of a system. The advantage of using feedback in conjunction with real-time scheduling is that precise schedulability models are no longer needed.