AWS: Developers Guide to AWS Lambda The Ultimate Beginners Guide

Amazon Web Services (AWS) Lambda lets you run JavaScript (Node.js), Java & Python scripts/apps in Amazon's (virtually) infinately-scalable cloud environment without having provision VM instances or other "orquestration"; Everything is dynamically auto-scaled so if you have 1 user or 1 billion you pay for usage.
AWS are effectively disrupting their (own) existing business with Lambda. Instead of forcing us to pay for EC2 instances in fixed increments and have complex application monitoring/scaling, AWS have built a much simpler way of building & running micro-services.
Lambda also disrupts other Platform-as-a-Service ("PaaS") providers such as Heroku, Google App Engine, Azure or Modulus where you pay for a specific amount of compute power & RAM but have a scaling delay and scale in a fixed increment(instances).