The best way to think of the free tier to Amazon Web Services is as a stepping-stone. It's a way to get your feet wet with the basic mechanisms of AWS and EC2; to understand Amazon's way of handling virtual machine instances, storage, data, and networking; and to create something that can eventually be hosted on a full-blown, for-pay AWS instance. It's also a way to learn how to manage and constrain AWS usage -- if you're not careful you may end up paying for your "free" AWS usage after all.

In this article, we'll look at what the free tier offers you and on what terms, then take a closer peek at what's possible or practical within those constraints. In the long run, any serious AWS user will want to take fuller advantage of what the Amazon cloud has to offer -- but why not make the most of the free resources in the meantime? The free tier is a great way to find one's legs with AWS, start some projects, and maybe even build a functional application or three.

[ Also on InfoWorld: How to get started with Amazon EC2 | From Amazon to Windows Azure, see how the elite 8 public clouds compare in InfoWorld Test Center's review. | For the latest news and happenings, subscribe to the Cloud Computing Report newsletter. ]

As a side note, one of the more ominous statements in Amazon's documentation about the free tier is this little warning: "We may stop accepting new registrations for the Offer at any time." This may be boilerplate CYA on Amazon's part, but if you're thinking about setting up a free-tier account, you might as well do it now and get in on the action while it's available.

What do you get for your $0 a month?

The AWS Free Usage Tier provides you with a level of usage for many AWS components that is often just enough to get up and running. But even if it doesn't give you all the resources you might want to create something truly useful, you can certainly create something functional. Just don't expect it to scale well for unrestricted public use. Here's a rundown of some of the most useful AWS components and what you get with them on the free tier.

Server. You can run a micro instance of a Linux or Windows Server machine on EC2, configured with 613MB of RAM, for 750 hours per month. That's an entire month of free, continuous CPU usage.

Amazon maintains a catalog of AMIs (Amazon Machine Images), which let you run a slew of different Linux and Windows systems -- among them Ubuntu Server 12.04 and 12.10, Microsoft Windows Server 2008 and 2012, and Amazon's own Amazon Linux AMI.

Not every AMI is eligible to be run on the free tier (even when you use a micro instance), but the ones that can be are clearly marked. The AWS Marketplace also features tons of third-party application appliances and server available as AMI instances -- but again, not all can be run on the free tier.