# Scalability

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Scalability refers to how well a system can grow. 
That is increasing the ability to do whatever the system is supposed to do. 
For example, a [Kubernetes](https://glossary.cncf.io/kubernetes/) [cluster](https://glossary.cncf.io/cluster/) scales by 
increasing or reducing the number of [containerized](https://glossary.cncf.io/containerization/) apps, 
but that scalability depends on several factors. 
How many [nodes](https://glossary.cncf.io/nodes/) does it have, how many [containers](https://glossary.cncf.io/container/) can each node handle, 
and how many records and operations can the control plane support?

A scalable system makes it easy to add more capacity. 
We differentiate between two scaling approaches. 
On the one hand, there is [horizontal scaling](https://glossary.cncf.io/horizontal-scaling/) which adds more nodes to handle increased load. 
In contrast, in [vertical scaling](https://glossary.cncf.io/vertical-scaling/) individual nodes are made more powerful to perform more transactions 
(e.g. by adding more memory or CPU to an individual machine). 
A scalable system is able to change easily and meet user needs.

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- Canonical URL: https://glossary.cncf.io/scalability/
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