PostGIS is an extension of the PostgreSQL database. By using PostGIS, it becomes possible to save geographic (spatial) data, as points, lines and areas, together with it's attributes in the PostgreSQL database.
A good example of geographic data with attributes is addresses. Imagine that we have one table for road center lines (lines), and one table for house numbers (points). These two tables respectively have attributes attached to the spatial data, such as municipality, street name and so forth.
By using PostGIS together with QGIS, there are several advantages:
- If the database is online it is always available, no matter where you are
- Most GIS software can talk to PostGIS, not only QGIS
- It is possible to register data out in the field, by using Android smartphone / pad
- All the different users of the database have possibility to share data with each other
More will be written about PostGIS later, for now we suggest you have a look at: