At AWS re:Invent 2014, Werner Vogels (Amazon CTO) announced Amazon Lambda. He described it as “an event-driven computing service for dynamic applications” and it’s going to change the way you think about computing resources forever!

Instead of having dedicated resources on all the time to process code (via a cron / job queue / whatever), you can now have Lambda functions execute if and only if events happen. Triggering these events is as simple as uploading a file to an S3 bucket, or adding records to a DynamoDB or Kinesis stream.