For a concerns working both formal and informal organization are important. Formal organization originates from the set organizational structure and informal organization originates from formal organization. For an efficient organization, both formal and informal organizations are required. They are the two phase of a same concern.
Formal organization can work independently. But informal organization depends totally upon the formal organization. Formal and informal organization helps in bringing efficient working organization and smoothness in a concern.
Within the formal organization, the members undertake the assigned duties in co- operation with each other. They interact and communicate amongst themselves. Therefore, both formal and informal organizations are important.
When several people work together for achievement of organizational goals, social tie ups tends to built and therefore informal organization helps to secure co-operation by which goals can be achieved smooth. Therefore, we can say that informal organization emerges from formal organization.