People briefed on the project, which was two years in the making, say it was partly motivated by Amazon's success in offering two-day delivery, through its Amazon Prime, service and same-day delivery, which has been available for four years in some cities.

WSJ: Google Follows Amazon's Lead on New Shopping Site, Delivery, Other Services

Because I am an Amazon Prime member, I get free 2-day shipping and Amazon is still not collecting California sales tax, which I am supposed to pay on my own.

FORBES: Buying From Amazon Makes Me Feel Guilty

As originally reported on TechCrunch and then confirmed by Reuters, the search giant is apparently working on a same-day delivery service that could pit it against the likes of Amazon Prime, eBay Now and local dispatchers like Postmates' GetItNow.

ENGADGET

It also manufactures and sells the Kindle e-reader and strives to offer customers the lowest prices possible through low every day product pricing and free shipping offers, including through membership in Amazon Prime.

FORBES: #8 Amazon.com