There are several programs fulfilling the same or similar functions to be installed on a single system at the same time. For example, many systems have several text editors or different web browsers installed,Multimedia players,graphics editors at once.
galternatives is graphical setup tool for the alternatives system.A GUI to help the system administrator to choose what program should provide a given service.
The /etc/alternatives defines default applications for Unix/Linux system this includes the default application to handle web browser,splash etc..
Install Galternatives in Ubuntu
If you want to install galternatives you need to enter the following command
sudo apt-get install galternatives
This will complete the installation.Now if you want to open this application you need to run the following command
gksudo galternatives
You should see the following screen here you can choose which applications you want to use default
Galternatives version details