It is a procedural programming language oriented towards developing  
     maintainable real-time safety-critical applications. It was intended for
     DoD real-time embedded computer systems. 

Contribution:

     Ada promotes a disciplined and systematic style of programming.
     Ada introduced packages and generics.
     Its modulatity provided by packages and the separation of specifications
     and bodies is exceptionally useful.
     It supports and encourages Object Oriented Design.

Source: SIGPLAN notices