What is DevOps?

DevOps is the combination of cultural philosophies, practices, and tools that increases an organization’s ability to deliver applications and services at high velocity: evolving and improving products at a faster pace than organizations using traditional software development and infrastructure management processes. 
This speed enables organizations to better serve their customers and compete more effectively in the market.

let's look at a simple diagram to understand it:

Infinite Sign Represent its continuous never-ending process.

What is Automation, Scaling, Infrastructure in Devops?
1-Automation
Automating DevOps pipelines allows for iterative, incremental software updates to be deployed faster and more frequently. 
It provides tighter feedback loops between Dev and Ops teams so they can spend more time innovating instead of performing manual processes.

Automation is what helps teams scale DevOps from a lighthouse project to an essential practice across the entire IT estate. 
DevOps automation typically rings the continuous integration, continuous delivery (CI/CD) bell, but automating these foundational processes can extend well beyond developing code. 
More advanced organizations seek to automate all stages of the DevOps lifecycle including infrastructure provisioning, deployment, monitoring, testing, remediation, and so on.

2-Scaling
Scalabilig refers to the ability of the business to set up its systems to grow during times of high demand and scale back when demand decreases. The optimum environment for achieving the appropriate level of scalability is DevOps, thanks to specific techniques. People can interact, concentrate on their work, have more creative alternatives, and swiftly deploy software through these techniques.

Just to state an example:
During New Year mostly companies scale up their servers to cope up with the surge in demands
3-Infrastructure
Infrastructure as Code (IaC) is a technology that allows teams to manage the configuration of cloud infrastructure such as servers, virtual machines, storage, and networks, in a declarative manner. 
“Declarative” means that engineers can write a simple text-based template defining what they want to deploy, and the IaC platform deploys it automatically, ensuring it is exactly the same every time.

Just like a DevOps team uses source code versioning and container images to manage the development process, IaC enables DevOps and cloud architecture teams to manage infrastructure at scale. 
An IaC template creates the same environment every time it is run. DevOps teams can continuously test and evolve their templates until they reach an optimal environment setup for the applications and resources they want to run

DevOps is important because it's a software development and operations approach that enables faster development of new products and easier maintenance of existing deployments.