Introduction to Kubernetes - Run Docker Containers at Scale

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.

DNS is the distributed lookup system that turns a hostname such as getting-digital.net into the IP address a browser can connect to, by walking a chain of nameservers whose answers are then cached for a lifetime the domain's owner publishes.

SSL/TLS is the protocol that encrypts the connection between a browser and a server and, by way of a certificate signed by a certificate authority, proves the server is entitled to answer for the domain in the address bar.

A domain name is an address in the internet's public namespace that you rent through a registrar for a yearly fee, and it remains yours only while the registrar account holding it stays paid up and under your own control.

Unit testing is the practice of writing small automated checks that call one piece of code in isolation, a function, a class or a module, with known inputs and assert on its outputs, so that a change which breaks that behaviour fails a test within seconds of being made.

Full-stack development is the ability to build both halves of a web application: the front end that runs in the browser (HTML, CSS and JavaScript) and the back end that runs on a server (a language, a framework and a database), plus the API that joins them.

A framework is a body of code that imposes a structure on the application built with it: it decides how files are organised, when the application's own code is called and how its parts talk, whereas a library is code the application calls when it chooses.