answer added on 25/3/2012
client of a collaborative client-server platform. IBM Lotus Domino is the application server. Lotus Notes provides integrated collaboration functionality, including email, calendaring, contacts management, to do tracking, instant messaging, an office productivity suite (IBM Lotus Symphony), and access to other Lotus Domino applications and databases. Lotus Notes can also be integrated with additional collaboration capabilities including voice and video conferencing, online meetings, discussions, forums, blogs, file sharing, microblogs, and user directories. In addition to these standard applications the organization may use the IBM Lotus Domino Designer development environment and other tools to develop additional integrated applications such as request approval / workflow and document management.