Design History
The way to design and develop a web application has changed over the years. Since it’s inception, web application designs have involved some components. You’d have the browser, and the user interface inside of pages that were static, with your db as linux/unix commands in CGI/BIN format on the server side. In fact, this old web server was first incarnated as text only kermit application in the OS kernel. You’d write really simple command line programs like Kermit terminal app that could read kermit data in and out and interact with keyboard only. No browser, just data and client/server.
Jump to now
Modern implementations of web applications (any computer task can be considered an application) use services that run on the CPU’s on the server side, but that is also connected to things like DNS, globalized content and security clouds like cloudflare/AWS and others. The backends or web server are programmed in OOP languages like Java and Python and served in a load-balanced manner, meaning there is more than one host doing all the backend work of serving the site. In the case of AWS and google, that is through a service like AWS’s fleet technology can scale the size of the connection points for your application so it never slows down from CPU load.
Some terms:
VPC – Virtual PC
EC2 – Elastic Compute Cloud Service. A public or private VM instance that can host some web dev tech
SaaS – Software as a Service. The fashion in which a service is delivered to developer or customer on a platform like AWS or GCP(Google). Examples are based on subscriptions instead of one time purchases.
IaaS – Infrastructure as a Service. The way to minimize physical hardware by moving legacy IT systems to the cloud and to the compute cluster as virtual interfaces and web server services.
PaaS – Platform as a Service. You can think of paas as a combo of the hardware, software, and release cycle of a software or OS or Database and putting all this into virtual form so that they all become a single service based on business requirements rather than separate physical or monolithic items, as a more self contained system.