Marketplaces take an increasing share of online retail sales: 56% of B2C online retail spend came from marketplaces in 2017. This report uses the Forrester Analytics Online Marketplace Tracker methodology to examine 11 marketplaces across 16 countries to understand their share of the B2C eCommerce market and their growth trajectories from 2015 to 2018. This report also looks at marketplace expansion and brick-and-mortar stores' increasing investment in and sales through marketplaces.