AWS in Plain English

EC2

Should have been called
Amazon Virtual ServersUse this to
Host the bits of things you think of as a computer.It's like
http://www.linode.com","It's handwavy, but EC2 instances are similar to the virtual private servers you'd get at Linode, DigitalOcean or Rackspace.

IAM

Should have been called
Users, Keys and CertsUse this to
Set up additional users, set up new AWS Keys and policies.

S3

Should have been called
Amazon Unlimited FTP ServerUse this to
Store images and other assets for websites. Keep backups and share files between services. Host static websites. Also, many of the other AWS services write and read from S3.

S3 in Plain English S3 Buckets of Objects

VPC

Should have been called
Amazon Virtual Colocated RackUse this to
Overcome objections that "all our stuff is on the internet!" by adding an additional layer of security. Makes it appear as if all of your AWS services are on the same little network instead of being small pieces in a much bigger network.It's like
If you're familar with networking: VLANs

Lambda

Should have been called
AWS App ScriptsUse this to
Run little self contained snippets of JS, Java or Python to do discrete tasks. Sort of a combination of a queue and execution in one. Used for storing and then executing changes to your AWS setup or responding to events in S3 or DynamoDB.

Lambda in Plain English

API Gateway

Should have been called
API ProxyUse this to
Proxy your apps API through this so you can throttle bad client traffic, test new versions, and present methods more cleanly. It's like
3Scale

RDS

Should have been called
Amazon SQLUse this to
Be your app's Mysql, Postgres, and Oracle database.It's like
Heroku Postgres

Route53

Should have been called
Amazon DNS + DomainsUse this to
Buy a new domain and set up the DNS records for that domain.It's like
DNSimple, GoDaddy, Gandi

SES

Should have been called
Amazon Transactional Email Use this to
Send one-off emails like password resets, notifications, etc. You could use it to send a newsletter if you wrote all the code, but that's not a great idea.It's like
SendGrid, Mandrill, Postmark

Cloudfront

Should have been called
Amazon CDNUse this to
Make your websites load faster by spreading out static file delivery to be closer to where your users are. It's like
MaxCDN, Akamai

CloudSearch

Should have been called
Amazon Fulltext SearchUse this to
Pull in data on S3 or in RDS and then search it for every instance of 'Jimmy.'It's like
Sphinx, Solr, ElasticSearch

DynamoDB

Should have been called
Amazon NoSQLUse this to
Be your app's massively scalable key valueish store.It's like
MongoLab

Elasticache

Should have been called
Amazon MemcachedUse this to
Be your app's Memcached or Redis.It's like
Redis to Go, Memcachier

Elastic Transcoder

Should have been called
Amazon Beginning Cut ProUse this to
Deal with video weirdness (change formats, compress, etc.).

SQS

Should have been called
Amazon Queue Use this to
Store data for future processing in a queue. The lingo for this is storing "messages" but it doesn't have anything to do with email or SMS. SQS doesn't have any logic, it's just a place to put things and take things out.It's like
RabbitMQ, Sidekiq

WAF

Should have been called
AWS FirewallUse this to
Block bad requests to Cloudfront protected sites (aka stop people trying 10,000 passwords against /wp-admin)It's like
Sophos, Kapersky

Cognito

Should have been called
Amazon OAuth as a ServiceUse this to
Give end users - (non AWS) - the ability to log in with Google, Facebook, etc. It's like
OAuth.io

Device Farm

Should have been called
Amazon Drawer of Old Android DevicesUse this to
Test your app on a bunch of different IOS and Android devices simultaneously.It's like
MobileTest, iOS emulator

Mobile Analytics

Should have been called
Spot on Name, Amazon Product Managers take noteUse this to
Track what people are doing inside of your app.It's like
Flurry

SNS

Should have been called
Amazon MessengerUse this to
Send mobile notifications, emails and/or SMS messagesIt's like
UrbanAirship, Twilio

CodeCommit

Should have been called
Amazon GitHubUse this to
Version control your code - hosted Git.It's like
Github, BitBucket

Code Deploy

Should have been called
Not badUse this to
Get your code from your CodeCommit repo (or Github) onto a bunch of EC2 instances in a sane way.It's like
Heroku, Capistrano

CodePipeline

Should have been called
Amazon Continuous IntegrationUse this to
Run automated tests on your code and then do stuff with it depending on if it passes those tests.It's like
CircleCI, Travis

EC2 Container Service

Should have been called
Amazon Docker as a ServiceUse this to
Put a Dockerfile into an EC2 instance so you can run a website.

Elastic Beanstalk

Should have been called
Amazon Platform as a ServiceUse this to
Move your app hosted on Heroku to AWS when it gets too expensive.It's like
Heroku, BlueMix, Modulus

AppStream

Should have been called
Amazon CitrixUse this to
Put a copy of a Windows application on a Windows machine that people get remote access to.It's like
Citrix, RDP

Direct Connect

Should have been called
Pretty spot on actuallyUse this to
Pay your Telco + AWS to get a dedicated leased line from your data center or network to AWS. Cheaper than Internet out for Data.It's like
A toll road turnpike bypassing the crowded side streets.

Directory Service

Should have been called
Pretty spot on actuallyUse this to
Tie together other apps that need a Microsoft Active Directory to control them.

WorkDocs

Should have been called
Amazon Unstructured FilesUse this to
Share Word Docs with your colleagues.It's like
Dropbox, DataAnywhere

WorkMail

Should have been called
Amazon Company EmailUse this to
Give everyone in your company the same email system and calendar.It's like
Google Apps for Domains

Workspaces

Should have been called
Amazon Remote ComputerUse this to
Gives you a standard windows desktop that you're remotely controlling.

Service Catalog

Should have been called
Amazon Setup AlreadyUse this to
Give other AWS users in your group access to preset apps you've built so they don't have to read guides like this.

Storage Gateway

Should have been called
S3 pretending it's part of your corporate networkUse this to
Stop buying more storage to keep Word Docs on. Make automating getting files into S3 from your corporate network easier.

Data Pipeline

Should have been called
Amazon ETLUse this to
Extract, Transform and Load data from elsewhere in AWS. Schedule when it happens and get alerts when they fail.

Elastic Map Reduce

Should have been called
Amazon HadooperUse this to
Iterate over massive text files of raw data that you're keeping in S3.It's like
Treasure Data

Glacier

Should have been called
Really slow Amazon S3Use this to
Make backups of your backups that you keep on S3. Also, beware the cost of getting data back out in a hurry. For long term archiving.

Kinesis

Should have been called
Amazon High ThroughputUse this to
Ingest lots of data very quickly (for things like analytics or people retweeting Kanye) that you then later use other AWS services to analyze.It's like
Kafka

RedShift

Should have been called
Amazon Data WarehouseUse this to
Store a whole bunch of analytics data, do some processing, and dump it out.

Machine Learning

Should have been called
SkynetUse this to
Predict future behavior from existing data for problems like fraud detection or "people that bought x also bought y."

SWF

Should have been called
Amazon EC2 QueueUse this to
Build a service of "deciders" and "workers" on top of EC2 to accomplish a set task. Unlike SQS - logic is set up inside the service to determine how and what should happen.It's like
IronWorker

Snowball

Should have been called
AWS Big Old Portable StorageUse this to
Get a bunch of hard drives you can attach to your network to make getting large amounts (Terabytes of Data) into and out of AWS It's like
Shipping a Network Attached Storage device to AWS

CloudFormation

Should have been called
Amazon Services SetupUse this to
Set up a bunch of connected AWS services in one go.

CloudTrail

Should have been called
Amazon LoggingUse this to
Log who is doing what in your AWS stack (API calls).

CloudWatch

Should have been called
Amazon Status PagerUse this to
Get alerts about AWS services messing up or disconnecting.It's like
PagerDuty, Statuspage

Config

Should have been called
Amazon Configuration ManagementUse this to
Keep from going insane if you have a large AWS setup and changes are happening that you want to track.

OpsWorks

Should have been called
Amazon ChefUse this to
Handle running your application with things like auto-scaling.

Trusted Advisor

Should have been called
Amazon PennypincherUse this to
Find out where you're paying too much in your AWS setup (unused EC2 instances, etc.).

Inspector

Should have been called
Amazon AuditorUse this to
Scans your AWS setup to determine if you've setup it up in an insecure wayIt's like
Alert Logic