The communication between two or more processes or two or more applications can be synchronous or asynchronous. Message queues are one of the fundamental techniques used for passing messages between applications. 

Amazon SQS is a scalable messaging queue service that can be used to pass messages between different components of an application, thus helping to decouple the application components. SQS also allows developers to save messages or data that might get lost if the application or its components goes down.

Amazon SQS supports both standard queues as well as First-In-First-Out (FIFO) queues.

The following are the typical uses cases of implementing the SQS service in your application:

• Application decoupling: The components of an application can be decoupled and they can talk to each other using messages queues; thus, each component of the application can be managed independently without affecting other components.
• Work queue and concurrently: You can create a queue of work items that can be consumed by the worker application. As the load of the queue increases, you can spawn more worker applications to balance to load.
• Transparent scaling: The SQS service can scale to handle the load without any manual intervention, which could be caused because of  occasional load spikes from the requester application.

Let's start writing some code and see how we can create and use a queue using the SQS service.