Importance of system analysis and design:
- mainly deals with software development
- system thinking is integral to the system
- provides a frame work for visualising the organization.
Open System:
- has many interfaces with its environment.
- permits interaction across its boundary.
- receives inputs and delivers output to outside.
Closed System:
- isolated from environmental influences.
- completely rare.
Characteristics of Open System:
- input from outside.
- Entropy
- Process, output, cycles

Data Dictionary:
- a term for dictionary.
- contains detailed information.
- collection of description of the data objects.
- structured in tables and views.
- an integral part of data base.
- holds the information about the data base.

Data Flow Diagram:
- graphical representation of flow of data.
- consists of series of bubbles joined by lines. Bubbles represent data transformation and lines represent flow of data.
- used for visualization of data processing.
- provides no information of timing of process.
- also known as bubble chart.