When launching GRASS GIS for the first time, you will open a default Location "world_latlog_wgs84" where you can find a map layer called "country_boundaries" showing a world map in the WGS84 coordinate system.

The main component of the Data tab is the Data Catalog which shows the GRASS GIS hierarchical structure consisting of Database , Location and Mapset .

GRASS Database (directory with projects)
  Running GRASS GIS for the first time, a folder named "grassdata" is automatically created. Depending on your operating system, you can find it in your $HOME directory (*nix) or My Documents (MS Windows).
Location (a project)
  A Location is defined by its coordinate reference system (CRS). In the case of the default Location, it is a geographic coordinate reference system WGS84 (EPSG:4326). If you have data in another CRS than WGS84, you should create a new Location corresponding to your system.
Mapset (a subproject)
  Each Location can have many Mapsets for managing different aspects of a project or project's subregions. When creating a new Location, GRASS GIS automatically creates a special Mapset called PERMANENT where the core data for the project can be stored.

For more info about data hierarchy, see GRASS GIS Database page.

## GRASS started in the default Location, now what?

First, if you would like to get to know GRASS better before importing your own data, please download provided samples such as the "North Carolina" dataset. You can simply reach them through "Download sample location to current database" management icon .

To work with your own data, you typically want to first create a new Location with a coordinate reference system (CRS) suitable for your study area or one that matches your data's CRS. The Location Wizard will help you with that by guiding you through a series of dialogs to browse and select predefined projections (also via EPSG code) or to define individual projections.

### Creating a New Location with the Location Wizard

If you know the CRS of your data or study area, you can fill EPSG code or description and Location Wizard finds appropriate CRS from a predefined list of projections. If you do not know CRS of you data, you can read it from your georeferenced data file (e.g. shapefile or GeoTiff file with the related metadata properly included).

### Importing data

After creating a new Location, you are ready to import your data. You can use simple raster or vector data import , or a variety of more specialized tools. If the data's CRS does not match your Location's CRS, data will be automatically reprojected. After import your raster or vector data are added as a layer to Map Display. To change layer properties, go to Display tab. To analyze your data, search for a tool in the Modules tab.

## Text-based startup and Location creation

GRASS GIS can be run entirely without using the graphical user interface. See examples of running GRASS GIS from a command line.

## See also

GRASS GIS 8 Reference Manual
GRASS GIS 8 startup program manual page
GRASS GIS tutorials and books

List of EPSG codes (Database of worldwide coordinate systems)