Amazon's aim is to have Alexa indistinguishable from a human voice.
The Echo is activated someone saying Alexa or Amazon, or Echo at which point it begins streaming spoken requests to the cloud where they are analysed using neural network technology in order to generate the right response to questions such as "Alexa, will it rain tomorrow?
It can play music from streaming services such as Amazon Music and Spotify, or play audio books from Audible.
The Echo has evolved into a digital home hub and allows users to control - by voice - things like lights, switches, and thermostats, while other companies can also offer 'skills' - like apps to connect to their own services.
As such, the Echo and Alexa have become Amazon's counter to Siri and Google Now.
But while using your voice is a simple way to control a device, building the hardware and software to make that possible involved solving some major problems, says Limp.