WalMart is the biggest retailer in the world. What uses of the internet have helped Wal-Mart become the biggest retailer in the world?

The most important thing that Wal-Mart has done with the
internet to become the world's largest retailer is to manage their supply chain via the
internet.  This has been much more important to Wal-Mart than actually selling products
over the internet.

Wal-Mart's major selling point is that
they are a low-cost retailer.  Wal-Mart is able to keep their costs low in part because
they work closely with their suppliers.  This has allowed Wal-Mart, for example, to keep
lower levels of inventory than other retailers.  They use the internet to coordinate
operations with their suppliers so as to always have enough inventory, but not an
excessive amount that will incur things like storage
costs.

By managing their supply chain via the internet,
Wal-Mart has helped itself become the world's leading retailer.