Walmart has cornered the market on delivering everyday household items at the lowest prices possible, but now it's looking to a particular segment of shoppers online for its next big push: Walmart is now testing an initiative to expand online grocery buying and pickup.

The test project is called Walmart To Go, which the world's largest retailer started testing in 2011 in San Jose and San Francisco, Ca. In late 2013, Walmart expanded the program to Denver, Co. In a lot of cases, the Walmart To Go was only available for home delivery of general home merchandise. But in the Denver area today, Walmart expanded the program to include a local grocery pickup option.

Denver area customers will now have the option to order their groceries online and pick them up at a nearby store at a designated pickup spot or at the drive-through pharmacy, if that's available. Walmart shoppers can order dry and frozen groceries online -- as well as fresh meat, produce, and bakery items -- and pick them up on the same day. The idea is convenience: To let customers order groceries from their desks in the morning and pick them up on the way home from work.

Online Groceries: The Next Big Retail Battleground

The idea is also to tap into (and dominate) a segment of shopping that is reliable, frequent, and more resilient to economic downturns than retailing home appliances, electronics, and other Walmart stalwarts. Big retailers are looking for convenience grocery shopping online as their competitive advantage over the local grocery store, and the competition to get there first and best is heating up.

According to Forbes, Walmart is seeing competitors Amazon.com and Peapod -- one of the first, and the most successful, online grocery delivery services. Amazon, for example, is testing out "AmazonFresh," which is currently only available in the Los Angeles, Seattle, and San Francisco areas. Amazon's grocery service promises that you can "place your order by 10 am and have it by dinner, or by 10pm and have it by breakfast," and provides local restaurant food, fresh produce and grocery deliver, as well as over half a million Amazon.com items in its same-day delivery service.

One of the ways they're pushing grocery shopping forward is through mobile -- the fastest growing segment of IT in the U.S. Peapod is testing out a "virtual store" where shoppers can order groceries on-the-go by scanning barcodes. It's little more than an advertisement poster with an app functionality so urban commuters can order food while they're waiting for the train, but the fact that Peapod is trying it shows that competition (driving the company's need for experimentation and innovation) are swiftly headed to its doorstep.

Who knows. Soon groceries may be swiftly headed to yours.