Millennials are causing change — everywhere. Millennials are changing the workplace, the home and everything in between. The sharing economy is one of the changes from this generation, and it doesn't seem to be going anywhere.

What is the sharing economy? According to Benita Matofska, founder of The People Who Share, a U.K.-based nonprofit whose mission is to mainstream the sharing economy, it's a "socioeconomic ecosystem built around the sharing of human and physical resources. It includes the shared creation, production, distribution, trade and consumption of goods and services by different people and organizations."

From Uber to Kickstarter, the sharing economy is ubiquitous — even catching the nickname P2P, or peer to peer. These companies are connecting individuals whose wants and needs align. For example, a guy in Chicago has an apartment that he needs to be rented for a few months over the summer. He can use airbnb to find someone to fill this vacancy.

One of the newest additions to this sharing economy is P2P grocery shopping, specifically Instacart.

What is Instacart?

Instacart connects an individual with personal shoppers in the area who pick up and deliver groceries. Currently, the service is offered in many areas, including Boston, Chicago, Houston, Los Angeles, New York City and Washington, D.C. The service is constantly spreading and upgrading, so it could be coming to your city before you know it.

Not only should consumers be excited for the Instacart expansion, but so should grocery retailers. Instacart partners with local grocery stores to offer its customers the best options. One of the most well-known partnerships currently is with Whole Foods.

Whole Foods began its partnership with Instacart last fall. Through the arrangement, Instacart was able to offer better rates at Whole Foods than other stores who are not partnered with them. The statistics from the partnership show the success.

"Whole Foods Market is now providing fresh grocery delivery options to more homes in America than any other food retailer," said Emily Wright, global media relations specialist at Whole Foods Market. That is all thanks to the partnership with Instacart.

"Since announcing our 15-market partnership with Instacart in September, our average weekly online delivery sales have already passed the $1 million mark," Wright said. "With online delivery sales as high as 5 percent of total sales in some stores, we are very excited about the future potential as we expand our reach to more markets, provide richer content highlighting our quality standards and broaden our product offering."

The Instacart-Whole Foods partnership is considered a success based on sales figures alone. But the attitude of the partners also shows success. Both sides of the partnership were pleased, and the partnership is pushing forward rather than staying stagnant.

"We ran an innovative promotion on Valentine's Day where we offered floral delivery in as little as one hour, with prices starting around $25 for a dozen of our high-quality, ethically sourced Whole Trade roses," Wright said. "Orders could be placed in advance, and combined with the ability to include chocolates or other special treats. It was very well received by our shoppers."

By offering different angles, promotions, etc., the partnership is able to offer customers a better experience. And the customers are adapting to this quickly.

Photo: Instacart

What should grocery stores know about Instacart?

The success from the Whole Foods partnership should catch the attention of grocers nationwide. It's a way to increase your sales — just by forming a partnership. But, before you jump in head first, here are a few facts to help you understand Instacart better.

Instacart has a flat-rate delivery fee for customers. However, on top of that fee, retailers mark up the price of the items on Instacart. This does cause the price to be higher than what would be paid at the store, but for many the convenience is worth the extra money. It is predicted that the markups will be removed with time.

"It's a matter of time until all grocers on Instacart have no markups. It just takes time to get there," Instacart founder and CEO Apoorva Mehta told Forbes. "There's a delivery fee that's clear to you. That's something we share with customers. We believe in the long term it's best for customers to pay what they would be paying in the store plus delivery fee."

Instacart customers place their order online. They select what they want, and the personal shopper goes shopping with the list. However, many stores offer unique products not available in other stores. Would these items be available on the Instacart site?

Instacart was ready for this. All you have to do is create a special request. Therefore, if you offer specialty products, your customers won't have to sacrifice them for delivery.

Instacart does not offer deliveries for nongrocery items, though. You cannot purchase tobacco, gift cards, etc. You may purchase pet items, but not live animals.

Instacart does offer alcohol delivery. Even though Instacart has its own prices for food, it offers the in-store price of alcohol to customers. The customer must pay a delivery fee, but the item itself is the sale price at the store. The customer must also provide proof of age at time of delivery.

Will cancellations and returns hurt grocery stores?

There is little risk on the grocer with Instacart. Instacart takes the payment at the time of the order. Therefore, the grocery store will be paid when the shopper completes the shopping list. There is no chance of the groceries being delivered without payment.

If the customer decides there are certain items that were delivered that they don't want, they can take them back to the store for the refund — following the store's refund policy.

Instacart was named the No. 1 company on this year's Forbes America's Most Promising Companies list. It also recently announced a $220 million Series C funding round that valued the company at more than $2 billion.

Instacart is planning to revolutionize the grocery shopping experience. Grocery stores should all jump on board the bandwagon to see success in grocery delivery.