Sectoral: Clusters are groups of humanitarian organizations, both UN and non-UN, in each of the main sectors of humanitarian action, e.g. water, health and logistics. (See diagram).

IASC Designated: The clusters are formally designated by the IASC and have clear responsibilities for coordination. Clusters are created when existing coordination mechanisms are overwhelmed or constrained in their ability to respond to identified needs in line with humanitarian principles.

Partnerships: A cluster can include any number of UN agencies, NGOs, Red Cross/Red Crescent representatives and – at national and sub-national level – relevant government agencies. By working together, these organizations are not only able to provide better assistance to affected populations. They are also better equipped to coordinate their work with actors outside their sector.

Cluster Lead Agencies: Each cluster is headed by one or two Cluster Lead Agencies (CLAs) tasked with convening the cluster, facilitating cluster coordination and planning, serving as a global arbiter of related technical standards, managing information on cluster-related field operations, and acting as a “provider of last resort” (POLR) for ensuring essential programme delivery functions in challenging contexts.

Categories: There are two categories of clusters:

1. Global clusters, which are always active.
2. In-country clusters, which are activated as needed during a crisis (and time-bound as per the 2018 protocols). For more information on the difference between an officially IASC activated food security cluster and a food security sector, see 3.2.3.

Primary Coordination Tool: The cluster approach remains the primary tool used by humanitarian actors to ensure coordination (in non-refugee settings), improving financing, leadership, and partnership as well as joint strategic planning, to make humanitarian response more predictable and effective. However, it is not the only humanitarian coordination solution. In some cases, it may coexist with other forms of national or international coordination, and its application must consider the specific needs of a country and the context.

Though there has been changes in its structure since 2005, for example with the addition of the Food Security Cluster in 2011 (formally endorsed by the IASC in December 2010 and established in 2011), along with overall improvements brought on by IASC reform initiatives such as the Transformative Agenda, this overall approach has remained a key pillar of the international humanitarian coordination system. See more on the revised approach of the Early Recovery Cluster in 4.3.5.