# Containerization

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Containerization is the process of packaging of application code including libraries and dependencies required to run the code into a single lightweight executable—called [container image](https://glossary.cncf.io/container-image/). 
## Problem it addresses 

Before [containers](https://glossary.cncf.io/container/) became prevalent, organizations relied on [virtual machines](https://glossary.cncf.io/virtual-machine/) (VMs) to 
orchestrate multiple applications on a single [bare-metal machine](https://glossary.cncf.io/bare-metal-machine/). 
VMs are significantly larger than containers and require a hypervisor to run. 
Due to the storage, backup, and transfer of these larger VM templates, creating the VM templates is also slow. 
Additionally, VMs can suffer from configuration drift which violates the principle of [immutability](https://glossary.cncf.io/immutable-infrastructure/).

## How it helps

Container images are lightweight (unlike traditional VMs) and 
the containerization process requires a file with a list of dependencies. 
This file can be version controlled and the build process automated, 
allowing an organization to focus on other priorities 
while the automated processes take care of the build. 
A container image is stored by a unique identifier 
that is tied to its exact content and configuration. 
As containers are scheduled and rescheduled, 
they are always reset to their initial state which eliminates configuration drift.

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- Canonical URL: https://glossary.cncf.io/containerization/
- Status: Completed
- Last modified July 4, 2024: ` [EN] update containerization (#3007) ` ([d7dca23](https://github.com/cncf/glossary/commit/d7dca238cacfbf1c0b84f1e217dd369eca7a88a3))
- Source: https://github.com/cncf/glossary/blob/main/content/en/containerization.md
- License: [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/)