Dear Mohana,
As an addendum to the answer of our learned friend Mr.Babu Alexander, I would like to state that a manager handling industrial relations should be thorough with the various provisions of the Industrial Disputes Act,1947 and the relevant Rules framed thereunder. In nutshell, collective bargaining is the technique most preferred by the ID Act,1947 to achieve its objectives of prevention as well as resolution of industrial disputes. That's why compulsory provisions for espousal of disputes other than the non-employment of any individual workman by trade unions or a body of workmen,formation of works committee and grievance settlement committee, appointment of area wise/industry wise Conciliation Officers, constitution of Boards of Conciliation, recognition of protected workman status to office bearers of registered trade unions, classification of services into public utility services and non public utility services, restrictions on change in certain service conditions,strikes and lock outs, lay off, retrenchment or closure, transfer of undertakings have been elaborately provided under the various distinct chapters of the Act. Even in the process of adjudication, certain restrictions on representation of parties are introduced to avoid protracted litigation. In this back drop, if you try to understand the queries with reference to the definition clauses, things would be easier.