> For the complete documentation index, see [llms.txt](https://docs.paigo.tech/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.paigo.tech/overview/key-concepts.md).
# Key Concepts
This chapter introduces the most important concepts in Paigo and uses examples to help understand how those concepts can be used for real-world cases.
### Terminology
**Offering:** Offering represents a pricing plan of the product, or how the product is charged. *As an example, an offering called "Enterprise Plan" is priced $49 per month for subscribed SaaS customers.*
**Dimension:** Dimension represents a valuable product metric that SaaS customers can consume and be charged on. *As an example, a dimension for an API SaaS would be API requests and a dimension for a machine learning platform would be the minutes of GPU used.*
**Customer:** Customer represents a SaaS customer of the SaaS business who uses products and make payments for their usage.
**Measurement:** measurement represents the implementation of how dimension usage is measured, collected and tracked. *As an example, a dimension called Processing Time (Minutes) for a machine learning SaaS application needs a measurement to define how Paigo calculates the running time in the SaaS infrastructure (such as GPU running in a Kubernetes Pod) and the frequency for Paigo to sample the running time (such as every 30 seconds).*
### Use a typical CRM SaaS as an example
A CRM SaaS business manages an offering called "Basic Plan" that charges $1.30/email sent and $10/Seat. A customer called John Doe subscribes to this plan. These relationship is illustrated in the diagram below.
Each of the dimension in the above diagram may have a measurement assigned so that the usage can be measured, collected and tracked. The full picture is illustrated in the diagram below.