Kubernetes is a container orchestration system that provides tools for automating software deployment, scaling, configuration management and also provides fault tolerance capabilities.
The main strength of Kubernetes is its extensibility. With this, Kubernetes grows from an orchestration engine to a full platform to deploy and manage applications. Kubernetes operators are the primary pattern to extend its capabilities with new functionalities and expose it to cluster users.
Core concepts
Kubernetes node
Pod
Deployment
Interacting with the cluster
The API Server on the master node is the single entry point for interacting with the K8s cluster. It exposes commands and queries through an HTTP API (that can be authenticated). As such, it is totally possible to control an K8s cluster by using curl and issuing the appropriate HTTP requests. But obviously there are better ways of doing so, usually with tools that wrap the API requests with a better interface like a CLI or UI dashboard. kubectl is the main CLI tool used to interact with K8s clusters.