# Plans, limits, and what they govern

You now know the four objects: session, cluster, [workspace](/glossary/workspace), [organization](/glossary/organization). A **plan** bounds how much
of them you can have.

This lesson covers the concept. The operational side (reading usage, controlling spend, choosing a
tier for a team) lives in
[plans, usage, and billing](/lesson/workspaces-and-organizations/plans-and-billing), written for
whoever owns that decision.

## The one distinction worth learning now

A plan bounds two different things, and confusing them explains most of the surprises people hit.

**Capacity** is how much compute you can use in total over a [billing period](/glossary/billing-period).

**Concurrency** is how much can run *at the same time*.

They fail differently:

| | Symptom |
| --- | --- |
| Capacity exhausted | Work is refused, or the bill is larger than expected |
| Concurrency exhausted | Work is *accepted* but queues, so sessions and clusters take a long time to start |

The second is the one that gets misdiagnosed. A team well inside its capacity can hit concurrency
limits constantly, and it does not feel like a limit. It feels like the platform is slow.

## Why the distinction exists at all

Concurrency limits *simultaneous* resources because that is what the underlying machines actually
constrain. Capacity limits *accumulated* resources because that is what gets billed. A plan has to
bound both, or one of the two runs away.

## Try this

Open your organization's [dashboard](/glossary/dashboard) and find the usage panel. Two questions:

1. What is your capacity, and how much of it has this billing period used?
2. How many sessions and clusters can run at once?

If you cannot answer the second from the dashboard, that is worth knowing before a team hits it.

## Where to go for the rest

Everything operational is in the admin course:

- [Plans, usage, and billing](/lesson/workspaces-and-organizations/plans-and-billing), covering what
  to watch, where spend concentrates, and how to keep it predictable
- [Cost optimization checklist](/resources/cost-optimization-checklist), the working form of that

Current tier details are in the
[platform documentation](https://docs.eugo.io/docs/platform/billing), which stays accurate as plans
change. This course deliberately does not restate them.

## Where that leaves you

You have the whole shape now: code in a session, work on a cluster, both inside a workspace, owned by
an organization, bounded by a plan.

[Choose your next step by role](/lesson/getting-started-with-eugo/next-steps) to go deeper on whichever
part you actually need.

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Source: https://university.eugo.io/lesson/eugo-101/plans-and-limits