Closed Systems: A closed system is one that is isolated from its environment. Closed systems are self contained so that the external environment does not influence the behaviour of the system, nor does the system influence its environment.

Data Flow Diagrams (DFD): Data flow diagrams are a structured analysis technique the systems analyst can use to put together a graphical representation of how dataflow through an organization. The data flow approach includes describing the existing system, and then describing the logical data flow as it would occur in the improved system.

Entropy: It is a measure of disorder within a system. Entropy describes the state of a closed system (no inputs from outside the system) where all elements move towards disorganization and the inability to obtain and process inputs so the system is unable to produce outputs.

General Systems Theory: The concepts of systems are collectively referred to as the General Systems Theory. Besides focussing on all parts of a system, it helps communication among specialists in various fields.

 Information System: A formalised system (usually computer) that can collect, store, process, and report data from various sources to provide the information necessary for management decision making.

 Interface: A point of communication between two or more processes, persons or other physical entities.

Management Information System: A system for providing information for decision-making to all levels of the management.

Open Systems: In General Systems Theory, a system that interacts with its environment by accepting inputs and producing outputs. These are also computer hardware and software that can interact without modification with hardware or software obtained from other vendors.

System: People, machines and methods organized to accomplish a set of specific functions.

System Analysis: In system development, the systematic investigation of a real or planned system to determine the functions of the system and how they relate to each other and to other systems.

System Analyst: A person whose responsibility is to analyse, design, and develop information systems.

System Development Life Cycle: The different phases that a typical computer-based information system goes through in its development and use.

Flowchart: A flowchart is a set of symbols representing an activity. Flowcharts are widely used in systems work because they can graphically represent the interrelationships among elements in a system.

 Systems Analysis: It is the study of an existing system for the purpose of designing a new or improved system.

Systems Approach: It is a philosophy of structure which coordinates, in an efficient manner, the activities of an organization or a system.

System Conversion: It is a changing process from one system to another and occurs when the old system is completely abandoned upon implementation of the new system.

System Design: System design is the determination of the processes and data a new system will require. When the system is computer-based, the design can also include a specification of the types of equipment to be used.

System Development: The complete process from planning, analysing, then Life Cycle designing and then implementing the computer processes.

System Documentation: Documentation is a comprehensive documenting method for creating and updating and maintaining the system a standards manual whose format and organization would be a model for all documentation to be developed; and a standardized approach to documenting all systems.

System Evaluation: It is the process that helps a systems analyst decide the merits of a system before its final implementation and also assess the performance of the system from time to time.

System Implementation: System implementation is the acquisition and integration of the physical and conceptual resources that produce a working system.

System Life Cycle: The stages to first plan, then analyse, then design and then implement the system.

Boolean Search: Developed by George Boole, It is a search strategy for formulating search query expressed in terms of index terms (or key words), combined by the use of logical operators AND, OR, and NOT.

Feedback: The mechanism by which a system can modify/ improve its performance of a task by taking account of past performance.

Information Retrieval Systems: The system to store items of information that need to be processed, searched, retrieved and disseminated to various user population.

Information: Information is the symbolic element used for communicating knowledge irrespective of the nature (numerical, textual etc.), material carriers, form of presentation, etc. It refers to both substance or content of documents and to physical existence. The term is also used to designate both the message (substance and form) and its communication (act).

Management: Is a process and agency which directs and guides the operation of an organization in the realization of established aims.

Management Information System (MIS): A system which provides management with information it requires to monitor progress, measure performance, detect trends, evaluate alternatives, make decision and to take corrective action.

Model Base: It is a component of DSS, which provides the decision-maker with the ability to describe and analyse existing problems as well as to generate and compare alternative solutions. It comprised a library of models.

Structured decision: The decision tasks which are usually of a routine and repetitive nature and require little analysis or judgment. A definite procedure has been worked out for handling them.

Unstructured decision: The decision tasks which are usually of a non-routine and non-repetitive nature. There is no clear cut method for handling the problem because it has not arisen before

Data: Collection of facts made up of numbers, characters and symbol stored on a computer in such a way that it can be processed by the computer.

Database: An integrated collections of files of data stored in a structured form in a large memory, which can be accessed by one or more users at different terminals.

 DBMS: Database management system is a series of programmes that allow the user to easily create and modify databases.

Domain Expert: A person whose knowledge and experiences have been used to produce information about a specific area of interest and store it in an expert system.

Inference Engine: Inference Engine is another key component of all expert systems. It is responsible for interpreting the contents of the knowledge base in the context of a user-specified input or hypotheses in order to reach a goal or a conclusion. It can be divided into three parts i) Context Block ii) Inference (Reasoning) mechanism iii) Explanation facility

Knowledge Engineer: A person who works with a domain expert to encode the knowledge. In some cases the domain expert also acts as the knowledge engineer.

Knowledge Base: knowledge base is an essential module of all expert systems. It contains the formal representation of the information provided by the domain expert as encoded by the knowledge engineer.

Knowledge Acquisition Facility: New knowledge is generated with the assistance of this facility.

User Interface: User interface is a module of the expert system which permits the user to benefit from the system.

Cache Memory: A high speed temporary storage in the CPU for storing parts of a program or data during processing.

Binary Search: A search technique for sorted data. B-Tree: An indexed data storage method that is efficient for a wide range of data access tasks.

Index: A sorted list of key values from the original table along with a pointer to the rest of the data in each row.

Pointer: A logical or physical address of a piece of data.

RAID: Redundant Array of Independent Disks (RAID) is a disk drive system that consists of multiple drives with independent controllers. The goal is to split the data to provide faster access and automatic duplication for error recovery

Dependency: A dependency refers to the relationship amongst attributes elonging to the relation or different relations.

E-R Diagram: Entity-Relationship Diagram. A diagram that shows associations (relationships) between entities.

Foreign Key: A column in one table that is the primary key in a second table. It does not need to be a key in the first table.

Normalization: The process of creating a well-behaved set of tables to efficiently store data, minimize redundancy, and ensure data integrity.

Primary Key: A column or a set of columns that identify a particular row in a table. Relation: A relation is a table.

Relationship: An association between two or more entities.

Access Method: The method used to store, find and retrieve the data from a database.

Data Independence: Separates the data from the programme, which often enables data definition to be changed without altering the programme.

Data Integrity: Keeping accurate data which means few errors and the data reflect the true state of a database.

Schema: An overall conceptual or logical view of the relationships between the data in a database.

Subschema: A subset or transformation of the logical view of the database schema that is required by a particular user application programme.

Data Definition Language (DDL): A language used to define or describe the database entries and the relationship among the entities during the setup phase of a database management system.

Data Manipulation Language (DML): A language used to query the items in a database management system database.

SQL: Structured Query Language XML: The Extensible Markup Language (XML) is the universal format for structured documents and data on the Web.

QL: Query Language

HTML: Hyper Text Markup Language is a system of codes made up of tags and attributes that serve to identify parts and characteristics of HTML documents. Some tags provide document structure, others reference while some others provide files. Hyper text documents are electronic documents containing pointers to a web of interrelated documents. By clicking on these links; the related documents can also be accessed.

Hashing: Hash – addressing, a storage and access method in which data records are stored at an address that can be computed according to some mathematical hashing function, generally using the value of the primary key. Hash-addressing requires less storage than other indexing methods but some additional computation is needed.

Index: Index is an auxiliary data structure used to speed up access to a data set on the basis of the key value for each record. The index may actually contain the key values, and the pointers and the key may be used to generate the address of the pointer in the index. The index can be used to provide an order to the data records and to provide the direct access to the records in the data set.

Relational Algebra: The definition of operators that can be used on relations. The algebra combines the set operators union, intersection, difference and Cartesian product, plus the special relational operators SELECT, PROJECT and JOIN. The result of every operation on a relation is also a relation.

Venn Diagram: A graphic image consisting of circles that represents the logical relationship of two sets of information.

Truth Table : A table that describes a logic function by listing all possible input values and indicating for each combination the output value.

Wild Card : A pattern matching character.