Online to offline

Online to offline, commonly abbreviated to O2O, is a phrase that is used in digital marketing to describe systems enticing consumers within a digital environment to make purchases of goods or services from physical businesses.
What's O2O.
"O2O" means "Online To Offline" but also "Offline to Online", indicating the two-way flow between the online and the physical world, especially retail and ecommerce, but also between brand marketing and shopper or point-of-sale marketing efforts to influence purchase decisions. For example, consumers could see an ad online and be driven to visit the store, or be in a physical store but ultimately purchase online for a variety of reasons (selection, price, convenience, etc). There are many aspects to O2O, and businesses are increasingly challenged to satisfy consumers' expectations of a frictionless flow. 
Initially, the term was applied to QR code marketing efforts, but has since evolved. It is often confused with omni-channel, which refers to companies with an online store as well as physical retail locations.
Often, O2O implies an online trigger which prompts the customer to go to a physical location to complete their purchase, but it can also be the other way around: One aspect of newer O2O initiatives is the ability to pay online and then pick up a product in an offline place, such as the retailers' physical store or 3rd party locations. Another O2O feature is returning items purchased online to the retailers' offline location. 
Criticism.
In its early use, the phrase received criticism as illogical. However, its mass adoption has dulled much of this criticism.