1. Spatial Databases
SpatiaLite & PostGIS

2. Spatial Databases
An ordinary database has strings, numbers, and dates.
A spatial database adds one or more additional types for representing geographic features.
The basic geographic types are:
GEOMETRY (abstract superclass)
POINT (a single coordinate, usually but not necessarily two dimensional)
LINESTRING (a set of two or more coordinates, with a linear interpretation of the path between the coordinates)
LINEARRING (a linestring of three or more coordinates in which the start and end points are the same, usually used to build polygons)
POLYGON (a set of one or more closed linearrings, one exterior ring that defines a bounded area, and a set of interior rings that define exceptions (holes) to the bounded areas)
MULTIPOINT (a set of points)
MULTILINESTRING (a set of linestrings)
MULTIPOLYGON (a set of polygons)
GEOMETRYCOLLECTION (a heterogeneous set of geometries)

3. SpatiaLite Spatially enables SQLite
SQLite is a simple, robust, easy to use and really lightweight DBMS
Each SQLite database is simply a file
You can freely copy it, compress it, put it on a network
They are also portable; the same database file will work on Windows, Linux & MacOS

4. SpatiaLite Can be read by QGIS Analogous to an ESRI File Geodatabase
Comes with a standalone executable GUI tool
Can import and export ESRI shapefiles

5. PostGIS Spatially enables PostgreSQL
PostgreSQL is a FOSS robust enterprise relational database
Analogous to ESRI's Spatial Database Engine (SDE)
Developed by Refractions Research
Released in May 2001

6. PostGIS PostGIS data can be used by: QGIS UDIG GRASS GIS MapServer
GeoServer
OGR
ArcGIS