I want to Collect information about postgresql

Hi. We want to perform a project and We  will use rdbms in project.I want to learn some topics about postgresql .Firstly, is the postgresql database server  free. For example . is there any licence  and How much is support cost.Technically is the postgresql useful to develop a simualtion.I appreciate if you reply this mail as soon  as possible.

 

Thanks for answers  and helps.