Any worker may at some time have problems or concerns with their work, working conditions or relationships with colleagues that they wish to raise with management. They want the grievance to be addressed, and if possible, resolved. It is also clearly in an organisation's interests to resolve problems before they can develop into major difficulties.
Grievances are best dealt with at an early stage, informally, with the immediate line manager. However, organisations should have formal procedures in place to handle cases left unresolved. Pursuing the formal route should be a last resort rather than the first option.