High Availability: Refers to systems that are durable and likely to operate continuously without failure for a long time. For a solution architect this means making sure your application (hosted in AWS) is always available when a user/customer tries to access it.

Fault Tolerance: it is the property that enables a system to continue operation properly in the event of the failure of one or more of its components. A fault tolerant application (in AWS) would be where one of its web server can fail, and still serve traffic to visitors (and ever repair itself).

Scalability: The ability of a system to easily increase in size and capacity in a cost effective way (usually based on usage demand).

Elasticity: The ability of a system to increase and decrease in size (usually based on usage demand). In architecting applications, this usually refers to the ability of an application to increase and decrease server capacity on demand.

Cost Efficient: Choosing the correct options to make a system as inexpensive as possible.

Secure: Following proper security guidelines and practices to secure a system.

AWS Best Practices: A set of guidelines outlined by AWS that should be followed when provisioning and using their services.