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| 1 | +--- |
| 2 | +title: Runtime |
| 3 | +status: Completed |
| 4 | +category: concept |
| 5 | +tags: ["application", "", ""] |
| 6 | +--- |
| 7 | + |
| 8 | +## What it is |
| 9 | + |
| 10 | +A runtime, in general, executes a piece of software. |
| 11 | +It is an [abstraction](/abstraction/) of the underlying operating system that translates the program's commands into respective actions for the operating system. |
| 12 | + |
| 13 | +In the context of [cloud native](/cloud-native-apps/), _runtime_ generally refers to container runtime. |
| 14 | +A container runtime specifically implements the [Open Container Initiative](https://opencontainers.org/) specification to ensure consistent handling around different container orchestration technologies. |
| 15 | + |
| 16 | +## Problem it addresses |
| 17 | + |
| 18 | +Without the abstraction of a container runtime, the application would have to deal with all the mechanics of each operating system, increasing the complexity of running the app. |
| 19 | + |
| 20 | +## How it helps |
| 21 | +Container runtimes are a necessary component of container orchestrators such as Kubernetes. |
| 22 | +They handle the container lifecycle, which does mainly three things. |
| 23 | +First, it defines how container images are specified and how the runtime can retrieve them. |
| 24 | +Second, they handle how these images are unpacked, layered, mounted, and executed. |
| 25 | +Furthermore, runtimes manage hardware resources taking care of all these operating system-level actions. |
| 26 | +These include resource allocation and isolation. |
| 27 | +Over time, different container runtime products evolved, leading to the OCI Specification, |
| 28 | +which became the standard for container runtimes. |
| 29 | + |
| 30 | +Introducing this standard allows end users to combine any OCI-compliant runtime with any OCI-compliant container orchestrator (like Kubernetes). |
| 31 | + |
| 32 | +## Related terms |
| 33 | + |
| 34 | +- [Cloud Native](https://glossary.cncf.io/cloud-native-apps/) |
| 35 | +- [Containerization](https://glossary.cncf.io/containerization/) |
| 36 | +- [Container Orchestration](https://glossary.cncf.io/container-orchestration/) |
| 37 | +- [Microservices Architecture](https://glossary.cncf.io/microservices-architecture/) |
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