What is the Sahel?
The Sahel is a 1,000 kilometer wide grassland between the vast Sahara desert on the north and the African rainforest.
This area, which spans from the Atlantic Ocean to the Red Sea, is one of the most productive crop regions in Africa.
What is the Great Green Wall?
It's an African Union initiative that ultimately aims to recover the vulnerable ecosystem, improve food security and the sustainable use of water by combatting land degradation, desertification and drought across the Sahel region.
The initiative brings together more than 20 countries from the Sahelo-Saharan region, as well as regional and international organisations.
It started as a project planting trees along the Sahel region. But it evolved into something more comprehensive later.
"We moved the vision of the Great Green Wall from one that was impractical to one that was practical," says Mohamed Bakarr, the lead environmental specialist for Global Environment Facility.
"It is not necessarily a physical wall, but rather a mosaic of land use practices that ultimately will meet the expectations of a wall. It has been transformed into a metaphorical thing," Bakarr said.
What is the situation in the region?
According to the United Nations, approximately 20 million people living in the Sahel are undernourished.
What has been done so far?
A total of 2,963 hectare of degraded lands in the Sahel have been restored since the initiative started, Food and Agriculture Organization of the United Nations said.
What is land degradation?
Nearly three-fourths of the Sahel is estimated to have degraded to varying degrees over the past 50 years.
Land degradation is a process in which the value of the biophysical environment is affected by extreme weather conditions particularly drought, and human activities that pollute or degrade the quality of soils.
It negatively affects food production, livelihoods and the production and provision of other ecosystem goods and services.
According to the United Nations, land degradation causes a decrease of almost three percent of agricultural production per year, further endangering food security in the sub-region.
What is desertification?
Contrary to popular perception, desertification is not the loss of land to the desert or through sand-dune movement.
Desertification is a form of land degradation, by which fertile land becomes desert.
Agriculture is one of Africa's biggest employers. But, two-thirds of the continent is made up of desert and drylands already.
Is it working?
The initiative appears to be working.
"The first, biggest achievement of the Great Green Wall is the fact that people of those regions have accepted to work together, for a common goal," said Elvis Paul Tangam, the African Union Commissioner for the Sahara and Sahel Great Green Wall Initiative.
"The second achievement is that each of those countries developed national action plans. That is the biggest achievement, because now they own it. It's about ownership, and that has been the failure of development aid, because people were never identified with it. But this time they identify. This is our thing," Tangam added.