Geographic Information System/Geodatabase

Geodatabase
A geodatabase is a storage container for GIS data. Databases have many advantages over shapefiles such as:
 * speed
 * ability to hold vector and raster data
 * ability to restrict attributes to certain formats or range of values
 * ability to enforce rules on input
 * and many more.

The standard geodatabase contains two major structures that you should be aware of:
 * feature data set
 * feature class

A feature data set is simply a collection of feature classes. You can think of a feature data set as a folder inside of the database. A feature data set will contain one or more feature classes and all those feature classes must have the same coordinate system. In other words, a feature data set is a logical grouping of feature classes inside of a geodatabase.

A feature class is a collection of common features and is analogous to a single shapefile. Each feature class must have the same geometry, just like the shapefile.

(image of geo database browser)