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A GeoDatabase is a database designed to store, query, and manipulate geographic information and spatial data. It is also known as a spatial database.
Within a spatial database, spatial data is treated as any other data type. Vector data can be stored as point, line or polygon data types, and may have an associated spatial reference system. A GeoDatabase record can use a geometry data type to represent the location of an object in the physical world and other standard database data types to store the object's associated attributes. Some GeoDatabase, such as those used by ESRI in their ArcGIS software, also include support for storing raster data.
Many GeoDatabase have custom functions that allow the spatial data to be manipulated and queried using SQL, for example to find all the residents of an area within an exposure zone for a potential environmental hazard. However the spatial data in some GeoDatabase can only be accessed by using specialized client software.
Within a geographic information system (GIS) a spatial database is one component that can be used to store and manipulate data. Typically a complete system will also include client software to view and edit the data stored within the database. Like other spatial data formats GeoDatabase can also be used to serve data directly to web map server software, such as ESRI's ArcGIS Internet Map Server, MapServer and Google's mapping API.
The primary advantage of spatial databases, over file-based data storage, is that they let a GIS build on the existing capabilities of relational database management systems (RDBMS). This includes support for SQL and the ability to generate complex geospatial queries. Also, a database's client/server architecture supports multiple users simultaneously and lets them view, edit, and query the database without conflict.
Below is an EXAMPLE of a GeoDatabase showing some of the parts, or elements of a GeoDatabase. In this sample we see the Zoning GeoDatabase displayed.
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In ArcGIS, a file with a .lyr extension that stores the path to a source dataset and other layer properties, including symbology.
A .lyr file is directly readable only by ArcGIS software and other newer software applications. This file does not contain actual geographic data, but rather contains specifications for the presentation of other datasets. Such specifications include color shading, naming, label properties (font, color, placements, etc.). Such presentation properties are usually time consuming to create, so a .lyr file allows these settings to be saved and shared. In order to use a .lyr file, you must also have a separate data file with the same prefix name saved in the same filespace.