"Alexa" is the assistant-in-the-machine that comes on the Amazon Echo (just as an iPhone 6 comes with Siri). You activate the Echo by saying "Alexa". The author

"Alexa" is the assistant-in-the-machine that comes on the Amazon Echo (just as an iPhone 6 comes with Siri). You activate the Echo by saying "Alexa". The author is probably guessing that in context, you'll make the connection between the title "The $10 Echo" and the Echo's hotword (Alexa). I agree it'd be useful if there was a brief explanation at the beginning of the article.