There are many formal definitions describing what a committee is but the essence of all such definitions could be stated as:
"A committee is a group of people trying to accomplish something (the purpose) that cannot be better accomplished otherwise".
The success of any committee requires an understanding of this basic principle. Every committee needs a purpose. If you do not know what you are trying to accomplish, or have no purpose, then your committee is unlikely to succeed. And, that purpose needs to be clearly articulated so that all members understand and you can work collectively to achieve it.
Besides a purpose, people are a key ingredient in any committee.. If your purpose can be accomplished by one or two people without a group, then you don't need a committee. If accomplishing your purpose requires a group, then you require a committee made up of the right people and the right processes and procedures..