This document summarizes top e-commerce marketing channels in 2021. It discusses rising consumer expectations, increased competition for Google, and diversification of user acquisition channels as trends impacting the industry. The document also outlines the agenda for its presentation, including rankings of top retailers and shopping apps, shifts in app downloads, top e-commerce websites by traffic and performance, and key traffic channels driving e-commerce growth. Questions are posed about the best channels for building brand awareness, lead generation, and increasing sales as well as how to track traffic and key performance indicators.