K.T. is an Amazon “Vine Voice.” Amazon sends her free stuff; she, as an established and trusted reviewer, tests it out and writes reviews. During a recent gathering she joked with family that her spouse was wearing Vine socks, Vine jeans, a Vine shirt, Vine underwear, and had on Vine cologne. There are thousands of Vine Voices, but K.T. is almost certainly among the most prolific. Over the years, she has passed in and out of Amazon’s overall Top 100 reviewer rankings. The Times agreed to not identify her. For Vine reviewers, identifying information — names, email addresses, websites — can be construed as a solicitation for free products from non-Vine sources, which Amazon can decide is grounds for removal from the program.

And K.T. takes her responsibilities seriously, dedicating time to each new item that emerges from the boxes and writing reviews that are succinct but complete. She helps run an online community for other Vine Voices — there’s another Viner in her town; she traveled out of state to meet the co-moderator of her community, whom she considers a close friend — and has reshaped her life around the program. “It’s only been about three years,” she said, “so I’m sort of new.”

If you invested $5,000 in Amazon in August of 2007, when Vine was announced, your stock would now be worth more than $100,000. If, instead, you had started reviewing your Amazon purchases, built a reputation as a reliable reviewer, secured an invite to the Vine program, kept your head down, filed your assignments and avoided the occasional purges of reviewers, your take-home total might today exceed that number, although in somewhat less liquid forms: five vacuums here; 14 hard drives there; some laptops and cellphones; Bluetooth speakers, and headphones, and headsets, and, well, pretty much anything with Bluetooth, so much Bluetooth, mouthful after mouthful of blue teeth.

The program was intended, in the company’s telling, to help its vendors “generate awareness for new and prerelease products” by “connecting them with the voice of the Amazon community.” Then, as now, but especially then, the Amazon reviewer community was at turns close-knit and competitive.

“Being part of the Vine program at the very beginning gave me a sense of duty,” said Diana de Avila, who had already been writing Amazon reviews since the mid ’90s. “I thought, oh my gosh, this large, emerging company is just growing by leaps and bounds, and they wanted me to be part of this apparatus,” she said.