In the digital finance ecosystem, aggregators function as the glue that helps entities like businesses, governments and donors easily connect with a variety of payment platforms--like mobile money services or banks—and the customers who pay via those services. But as CGAP’s deck on aggregators explains, many aggregators function only in the background of transactions and do not directly engage with customers. How do these aggregators get off the ground, what is their size and reach, and what are some key components of their business model?