United Nations Office for the Coordination of Humanitarian Affairs

OCHA is the part of the United Nations Secretariat responsible for bringing together humanitarian actors to ensure a coherent response to emergencies. OCHA also ensures there is a framework within which each actor can contribute to the overall response effort. 
OCHA’s mandate stems from General Assembly (GA) resolution 46/182 of December 1991, which states: “The leadership role of the Secretary-General is critical and must be strengthened to ensure better preparation for, as well as rapid and coherent response to, natural disasters and other emergencies.” To this end, it also establishes the role of the Emergency Relief Coordinator (ERC), who works with the Secretary-General and the Inter-Agency Standing Committee (IASC) in leading, coordinating and facilitating humanitarian assistance. OCHA is the office that provides support to the ERC and the Secretary-General to meet the leadership and coordination responsibilities charted in GA resolution 46/182.
GA resolution 46/182 assigns a clear leadership and coordination role to the ERC for international humanitarian assistance to respond to the needs of affected people. This mandate extends to affected people in internally displaced persons (IDPs) situations and was reinforced by related GA resolutions (including GA resolution 70/165). This was also formally recognized in the Secretary-General’s 1997 reform agenda, which assigned the ERC with responsibility for the overall coordination of assistance to IDPs. The GA expressed support for the reform agenda, and in subsequent resolutions it has emphasized ‘the central role of the ERC’ for coordinating the protection of and assistance to IDPs.
The ERC is the global champion for people affected by emergencies and the principal adviser to the Secretary-General on all humanitarian issues. Through the ERC, OCHA amplifies the voices of affected people, champions humanitarian principles and action, and promotes solutions to reduce humanitarian need, risk and vulnerability. At the global, regional and country levels, OCHA convenes humanitarian partners for the coordinated, strategic and accountable delivery of humanitarian action. At the country level, the ERC maintains close contact with and provides leadership to United Nations Resident Coordinators/Humanitarian Coordinators (RCs/HCs) on matters related to humanitarian assistance.
OCHA coordinates humanitarian action to ensure crisis-affected people receive the assistance and protection they need. It works to overcome obstacles that impede humanitarian assistance from reaching people affected by crises, and it provides leadership in mobilizing assistance and resources on behalf of the humanitarian system. OCHA is not an operational agency directly engaged in the delivery of humanitarian programmes, and its added value is as an honest broker, facilitator, thought leader and global advocate, providing support to the humanitarian system. In fulfilling its coordination mandate, OCHA is guided by the humanitarian principles of humanity, neutrality, impartiality and independence.
If you are also looking for some boilerplate about the Centre for Humanitarian Data:

The Centre for Humanitarian Data is focused on increasing the use and impact of data in the humanitarian sector. It is managed by the United Nations Office for the Coordination of Humanitarian Affairs (OCHA). The Centre’s services are available to humanitarian partners and OCHA staff in the field and at Headquarters free of charge.

The Centre is focused on four areas: 1) data services; 2) data literacy; 3) data policy; and 4) network engagement. Our vision is to create a future where all people involved in a humanitarian situation have access to the data they need, when and how they need it, to make responsible and informed decisions.
The main outcomes we want to see include:

• Speed of data: We want to speed-up the flow of data from collection to use. We want to shift from using outdated information to understand humanitarian crises to having data that reflects a current day, real-time understanding of a crisis.
• Connections in the network: We want to increase the number of partners who are connected to the Centre and each other through a shared data infrastructure and shared data goals.
• Increased use: We want to make sure data is used better and more often by the people who are making critical decisions in a humanitarian response. We need to make sure data and related insights are accessible to non-technical people.