Kubernetes On The Cloud & The CNCF CKA Certification

Kubernetes is an open-source system that runs containers across a cluster of machines, keeping the number and placement of running copies matched to a declared desired state, and restarting, rescheduling and scaling them without a person intervening.

IaaS is the layer of cloud computing where you rent raw infrastructure through an API, meaning virtual machines, disks and networks, and take responsibility for the operating system and everything you install above it.

PaaS is a hosting layer that takes your source code and turns it into a running application for you, owning the machines, the runtime, the build, the routing, the certificates and the restarts, so that shipping becomes a push rather than a project.

Managed hosting is any plan where the provider runs the server on your behalf, covering updates, hardening, monitoring, backups and tuning, so the thing being sold is administration time with a machine attached rather than the machine itself.

Cloud hosting is the model in which servers, storage and databases are created on demand through an API from a provider's pooled hardware and billed for the time they exist, rather than rented as a fixed box by the month.

A web server is the program listening on a network port for HTTP requests and answering them, either by returning a file from disk or by handing the request to application code behind it.

A REST API exposes an application's data as resources at stable addresses and lets clients read and change them with HTTP's standard methods and status codes, so that the protocol itself carries most of the meaning.

JSON is a text format for exchanging structured data: values are strings, numbers, booleans or null, arranged in ordered arrays and in objects of name and value pairs, and every mainstream language reads and writes it without a library of its own.

GraphQL is a query language for APIs and a server-side runtime for answering those queries: a client asks for precisely the fields it needs from a typed schema, in one request, instead of calling several fixed endpoints and discarding most of what comes back.