At first glance, the U.S. e-commerce market has never looked healthier. U.S. online retail sales reached nearly $400 billion in 2016 according to the U.S. Commerce Department—a 15.6% jump compared with 2015. That’s the biggest jump in three years, and far eclipses the growth in retail sales in physical stores, which barely reached 2.6% last year.

E-commerce now comprises 11.7% of total retail sales when factoring out the sale of items not normally purchased online, such as fuel, automobiles and sales in restaurants. That means the web has more than doubled its share of retail sales over the past 10 years. But look a little closer and you see that the e-commerce picture is an increasingly lopsided one. There’s Amazon and then there’s everyone else.

A deeper dive into this strategy article will reveal what retailers—both big chains and smaller players—are doing to shift focus to digital and compete with the online giant. The piece features a number of charts showing historical trends in e-commerce penetration dating back to 2007, comparing online to total sales growth rates for retailers with store closings and offering the results of an exclusive survey that asked online shoppers where they go to start their search.