# From Definition to call

URL: /platform/lifecycle · Id: `page:/platform/lifecycle`

> The steps an API passes through, from the Definition a Startup writes to the call a Customer makes and the record it leaves.

An API moves from a written [Definition](/reference/concepts#definition) to served calls in the steps below, each one proven or ruled.

## The steps
| Step | What happens |
| --- | --- |
| 1. Author | Write the [Definition](/reference/concepts#definition) as data, as rows, with no deploy. |
| 2. Validate | The platform checks the Definition and refuses it with every problem named. |
| 3. Publish | Writing the [Product](/define/product) and its Offer records publishes the API. |
| 4. Mount | A host whose namespace defines an API serves it from that Definition. |
| 5. Derive | Every [Interface](/interfaces) and [machine register](/interfaces#machine-registers) is generated from the one Definition. |
| 6. Serve | Each call passes its gates in order, runs, and answers with its cost header. |
| 7. Meter | A priced call emits one usage Event, counted once by its token. |
| 8. Observe | The [Dashboard](/reference/concepts#dashboard) reads back the kept calls of one [Key](/callers/keys). |

## Why there is no deploy
A Definition is data, and so is how each [Operation](/define/operations) runs. Writing the records publishes the API, so a Startup ships an API without shipping code.