Broadly, their importance is for:
LIFE AND LIVELIHOODS
They support a quarter of all marine life, and the livelihoods of a billion people in over 100 countries, and they drive coastal economies through tourism, fishing and recreation.
They have a global economic value of $375 billion a year, and they provide food for hundreds of millions of people.
ENVIRONMENTAL
They protect coastlines from the damaging effects of wave action and storms, whilst acting as a filter.
They assist in carbon and nitrogen fixing which helps with nutrient recycling.