3-Tier Auto-scalable Web Application Architecture

"A web application or web app is any application software that runs in a web browser or is created in a browser-supported programming language (such as the combination of JavaScript, HTML and CSS) and relies on a common web browser to render the application. ... Applications are usually broken into logical chunks called "tiers", where every tier is assigned a role. ...
For more complex applications, a 3-tier solution may fall short, and it may be beneficial to use an n-tiered approach, where the greatest benefit is breaking the business logic, which resides on the application tier, into a more fine-grained model. Another benefit may be adding an integration tier that separates the data tier from the rest of tiers by providing an easy-to-use interface to access the data. For example, the client data would be accessed by calling a "list_ clients()" function instead of making an SQL query directly against the client table on the database. This allows the underlying database to be replaced without making any change to the other tiers." [Web application. Wikipedia]
The AWS architecture diagram example "3-Tier Auto-scalable Web Application Architecture" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the AWS Architecture Diagrams solution from the Computer and Networks area of ConceptDraw Solution Park.

"In computer networking, cloud computing is computing that involves a large number of computers connected through a communication network such as the Internet, similar to utility computing. ...
Network-based services, which appear to be provided by real server hardware, and are in fact served up by virtual hardware, simulated by software running on one or more real machines are often called cloud computing. Such virtual servers do not physically exist and can therefore be moved around and scaled up or down on the fly without affecting the end user, somewhat like a cloud becoming larger or smaller without being a physical object. ...
Typically, the seller has actual energy-consuming servers which host products and services from a remote location, so end-users don't have to; they can simply log on to the network without installing anything. The major models of cloud computing service are known as software as a service, platform as a service, and infrastructure as a service. These cloud services may be offered in a public, private or hybrid network. Google, Amazon,leadsquared.com, Oracle Cloud, Salesforce, Zoho, Access2MyPC, and Microsoft Azure are some well-known cloud vendors." [Cloud computing. Wikipedia]
The AWS architecture diagram example "2-Tier Auto-scalable Web Application Architecture in 1 AZ" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the AWS Architecture Diagrams solution from the Computer and Networks area of ConceptDraw Solution Park.