GIS data structure encompasses both spatial and attribute data, each playing a crucial role in representing geographic features and their associated attributes within a Geographic Information System (GIS). Here's an explanation of spatial and attribute data in GIS: 

SPATIAL DATA

Spatial data represent the geometric location and shape of geographic features on the Earth's surface. There are two primary types of spatial data in GIS:

1. VECTOR DATA
   
   • Vector data represent geographic features as discrete points, lines, and polygons.
   • POINTS: Represent specific locations on the Earth's surface, such as landmarks, cities, or sampling sites.
   • LINES (POLY LINES): Represent linear features such as roads, rivers, or pipelines.
   • POLYGONS: Represent areas or regions bounded by closed lines, such as countries, administrative boundaries, or land parcels.
   • Vector data can store additional attributes associated with each feature, such as population density for a city point, road name for a road segment, or land use type for a polygon.

2. RASTER DATA:

   • Raster data represent geographic features as a grid of regularly spaced cells or pixels, where each cell has a value representing a certain attribute or property.
   • Each cell in a raster grid corresponds to a specific geographic location and has an associated value, such as elevation, temperature, or land cover classification.
   • Raster data are particularly suitable for representing continuous phenomena, such as elevation surfaces, satellite imagery, or environmental variables.

ATTRIBUTE DATA

Attribute data, also known as tabular data or non-spatial data, represent the descriptive information or attributes associated with spatial features. Attributes provide additional context and characteristics about the geographic features represented by spatial data. Attribute data are typically stored in tabular format, where each row corresponds to a feature, and each column represents a specific attribute or property. Examples of attribute data include:

• FEATURE IDs: Unique identifiers for spatial features, used for linking spatial and attribute data. 
• FEATURE PROPERTIES: Descriptive attributes such as name, population, area, length, elevation, land use type, or any other characteristic associated with the features.
• CATEGORICAL VARIABLES: Nominal or ordinal variables representing categories or classes, such as land cover types, land use categories, or administrative divisions.
• NUMERICAL VARIABLES: Continuous or discrete numerical values representing measurements or counts, such as temperature, population density, or income levels.
• DATE AND TIME: Temporal attributes representing dates, timestamps, or time intervals associated with the features.

 INTEGRATION OF SPATIAL AND ATTRIBUTE DATA

In GIS, spatial and attribute data are integrated to provide a comprehensive representation of geographic features and their associated attributes. Spatial data provide the geometry and location of features, while attribute data provide the descriptive information and characteristics of those features. GIS software allows users to link spatial and attribute data through a unique identifier, enabling spatial analysis, visualisation, querying, and decision-making based on both spatial and attribute information.