Open source simply refers to making the source code of the software freely available for users or other developers to use and make changes into the original repository or fork the project into and build a new one. 

Open NMS (Network Management System) is a free and open-source initiative grade network monitoring and management platform. It is established and maintained by a community of users developers and by the open NMS group, it offering services, training and support.

NS2 is the abbreviation of NETWORK SIMULATOR version 2. It was considered explicitly for exploration in network communication and event-driven open-source simulator in computer.

A significant output of simulation is the trace files. Trace files can document every incident that happened in the simulation and are used for examination.

A network simulator is a software program that replicates the functioning of a computer network.In simulators, the computer network is typically demonstrated with devices, traffic etc. and the performance are evaluated.

Organization related to open source:
(i)  Apache Software Foundation
(ii)  Free Software Foundation
(iii) Linux Foundation
(iv) Open Source Initiative.

(i) In this period of increased competition and cyber crimes, the computers used by indivudals or business organisations may have spy hardwares of rivals.
(ii) Open source hardware technology helps in such threats.
(iii) In this technique we get the components of the hardware and its circuit diagram, so that we can remove suspicious spyware if found.

NS2, OPEN NMS, Ubuntu, MySQL, PDF Creator, Open Office, 7zip GNUCASH, GIMP, BLENDER, AUDACITY, VLC, MOZILA FIREFOX, MAGENTO, ANDROID, PHP.

(i) Free software is a concept developed in the 1980s by an MIT computer science researcher, Richard Stallman who defined four conditions, as outlined by the nonprofit Free Software Foundation.
(ii) These "four freedoms" emphasize the ability of users to use and enjoy software as they see fit.
(iii) Freeware usually refers to proprietary software that users can download at no cost, but whose source code cannot be changed.

(i) Software can be used without any cost and restrictions
(ii) Sharing of ideas with the team.
(ii) User friendly.
(iv) We can add the most required features in the software.
(v) We can learn many ideas.
(vi) We can make our program writing skills more efficient

OSS projects are collaboration opportunities that improve skills and build connections in the field.
Domains that developers can contribute to the open source community include:
1. Communication tools.
2. Distributed revision control systems.
3. Bug trackers and task lists.
4. Testing and debugging tools.
(i) There are many open source softwares. So, we can select and use any software that suits our needs.
(ii) The complete options of the software can be used without any cost and restrictions.
(iii) We can share our ideas with the team. write the required code and share it with many.
(iv) As we can identify the programming techniques of group members, we can learn many ideas and make our program writing skills more efficient.
(v) The coding in open source software are being groomed by many enthusiastical members of the groups. So, if we report problems that we have in the program they are quickly mended by the group's effort.
(vi) As we can make changes to the open source software, we can add the most required features in the software.
(vii) Many open source software are very user friendly.
 

Open Source Software	Proprietary Software
It refers to the software that is developed and tested through open collaboration.	It refers to the software that is solely owned by the individual or the organization that developed it.
Anyone with the academic knowledge can access, inspect modify and redistribute the source code.	Only the owner or publisher who holds the legal property rights of the source code can access it.
The project is managed by an open  source community of developers and programmers.	The project is managed by a closed group of individuals or team that developed it.
They are not aimed at unskilled users outside of the programming community.	They are focused on a limited market of both skilled and unskilled and users.
It provides better flexibility which means more freedom which encourages innovation.	There is a very limited scope of innovation with the restrictions and all.
Examples: Android, Firefox, Libreoffice, Ubuntu, Gname etc..	Examples: Windows, mac Os, iTunes, Google earth. Adobe flash etc.