Defination of GIS and its Components.

1. Geographic Information Systems (GIS) store, analyze, and visualize data for geographic
positions on Earth’s surface. GIS stands for Geographic Information Systems and is a
computer-based tool that examines spatial relationships, patterns, and trends in
geography.
GIS
"A Geo Information System is
a system for capturing,
storing, checking,
integrating, manipulating,
analysing, and displaying
data which are spatially
referenced to the Earth.
(P.Stefanovic)

2. Components of GIS

3. A GIS is an organized collection of computer hardware, software, geographic data, and
personnel designed to efficiently capture, store, update, manipulate, analyze, and display all
forms of geographically referenced information.
Hardware
Hardware is the computer on which a GIS operates. Today, GIS software runs on a wide
range of hardware types, from centralized computer servers to desktop computers used in
stand-alone or networked configurations.
Motherboard: It is board where major hardware parts are installed or It is a place where all
components gets hooked up.
Hard Drive: It is also called hard disk, place to store data.
Processor: Processor is the major component in computer, it performs calculation. It is
called as Central processing Unit (CPU).
RAM: Random Access Memory (RAM) where all running programs load temporarily.
Printer: It is output device and used to print image, map or document. There are various
type of printer available in market.
External Disk: These are portable storage space such as USB drive, DVD, CD or external disk.
Monitor: It is a screen for displaying output information. Nowadays there are various type
of monitor: CRT (cathode ray tube), LCD (Liquid Crystal Display), LED (Light Emitting Diodes)
and more.

5. Software
GIS software provides the functions and tools needed to store, analyze, and display
geographic information. It helps to query, edit, run and display GIS data. It uses RDBMS
(Relational Database Management System) to store the data. Few GIS software list:
ArcGis, ArcView 3.2, QGIS, SAGA GIS.
Software Components:
GIS Tools: Key tools to support the browsing of the GIS data
RDBMS: Relational Database Management System to store GIS data. GIS Software
retrieve from RDBMS or insert data into RDBMS.
Query Tools: Tools that work with database management system for querying, insertion,
deletion and other SQL (Standard Query Language).
GUI: Graphical User Interface that helps user and Software to interact well.
Layout: Good layout window to design map.

7. Data
Possibly the most important component of a GIS is the data. Geographic data and related
tabular data can be collected in-house or purchased from a commercial data provider. A
GIS will integrate spatial data with other data resources and can even use a DBMS, used
by most organizations to organize and maintain their data, to manage spatial data.
The data that a GIS operates on consists of any data bearing a definable relationship to
space, including any data about things and events that occur in nature. At one time this
consisted of hard-copy data, like traditional cartographic maps, surveyor’s logs,
demographic statistics, geographic reports, and descriptions from the field. Advances in
spatial data collection, classification, and accuracy have allowed more and more standard
digital base-maps to become available at different scales. Data are two types- Spatial and
Non spatial.
Spatial Data
Vector
Vector data is graphical representations of the real world. There are three main types of
vector data: points, lines, and polygons.
Connecting points create lines, and connecting lines that create an enclosed area create
polygons.

8. Point Data-
Data points, also known as data items, are the atomic state of data. Conceptually, you can
think of them as one cell in a data table, or one piece of information, about an
observation, at a given point in time.
Line Data-
Line (or arc) data is used to represent linear features. Common examples would be rivers,
trails, and streets. Line features only have one dimension and therefore can only be used
to measure length.
Area Data- Area data is used to represent polygon features. Common examples would be
forest, agricultural land, water body. Polygon features have two dimension and therefore
can be used to measure area.

9. Raster
Raster data is data that is presented in a grid of pixels. Each pixel within a raster has a
value, whether it be a colour or unit of measurement. This communicates information
about the element in question. Rasters typically refer to imagery. However, in the spatial
world, this may specifically refer to orthoimagery which are photos taken from satellites
or other aerial devices. Raster data quality varies depending on resolution and your task
at hand.
Attribute data are non-spatial characteristics that are connected by tables to points,
lines, “events” on lines, and polygons (and in some cases GRID cells)A point, vector or
raster geologic map might describe a “rock unit” on a map with a single number, letter or
name, but the associated attribute table might have age lithology percent quartz etc, for
each rock type on the map.
Data
Possibly the most important component of a GIS is the data. Geographic data and related
tabular data can be collected in-house or purchased from a commercial data provider. A
GIS will integrate spatial data with other data resources and can even use a DBMS, used
by most organizations to organize and maintain their data, to manage spatial data.
People
GIS technology is of limited value without the people who manage the system and
develop plans for applying it to real-world problems. GIS users range from technical
specialists who design and maintain the system to those who use it to help them
perform their everyday work.