# Glossary

> The words Flozu uses, in one place.

**Auto-scaling.** A part that runs more copies of itself as traffic grows. See [auto-scaling](https://docs.flozu.app/guides/traffic-and-limits.md#auto-scaling).

**Blast radius.** Everything a failure touches, and how much of the traffic fails where it starts. See [failure drills](https://docs.flozu.app/guides/failure-drills.md).

**Bundle.** One `.flozu-bundle.json` file holding several maps, with their folders and, if you like, their versions and proposals. See [import and export](https://docs.flozu.app/guides/import-export.md).

**Buffer.** How much a queue or topic can hold while it waits to be worked through. Shown as **Holds** in the inspector.

**Capacity.** The most a part can handle each second. More than this backs up.

**Copy.** One running instance of a part that auto-scales.

**Draft.** A scenario you’ve changed but not saved with the map. It belongs to this window only.

**Drawing.** The small live picture in a part’s panel. Any part can show any drawing.

**Drill.** A scenario that takes a part, a line or a zone down for a while, to see what fails and what takes over. See [failure drills](https://docs.flozu.app/guides/failure-drills.md).

**Entry point.** A part no line flows into, such as people or an app. Scenarios scale the traffic that starts there.

**Estimate.** A scenario’s rough figure for how long requests take, how much fails, or what the map costs to run, worked out from the map rather than measured. See [response times and cost](https://docs.flozu.app/guides/response-times-and-cost.md).

**Limit.** The most a part lets through each second. The rest is turned away.

**Line.** A connection between two parts, carrying requests or messages. Called a connection in the file format.

**Map.** One document holding parts, lines, zones, notes, views, stories and saved scenarios.

**Map inside.** Another map a part opens into, to show what’s inside it. See [maps inside parts](https://docs.flozu.app/guides/maps-inside-parts.md).

**Message.** Traffic that’s sent and left, like an event or a job. Drawn as a dashed lime line.

**Moment.** A point in a scenario worth stopping at, such as the busiest moment or when a part first runs over.

**Note.** Plain words on the canvas.

**Part.** A piece of the system, such as a service or a database. Called a component in the file format.

**Preset.** A ready-made part on the library’s Presets shelf, such as a Redis cache.

**Project.** A folder at the top level, holding maps and folders. The **Maps** panel lists each one as a tree.

**Proposal.** A copy of a map to change freely, which remembers where it began so it can be compared and adopted.

**Rate.** How much a line carries each second at the busiest moment of a normal day.

**Replay.** The same scenario played on two maps, such as a proposal and where it began, to see what a change does to how the map copes. See [replay a scenario](https://docs.flozu.app/guides/versions-and-proposals.md#replay-a-scenario).

**Request.** Traffic that asks and waits for an answer, like an HTTP call. Drawn as a solid pale blue line.

**Response time.** How long a request takes, its part’s own time and the time of the requests that part makes in turn. A scenario [estimates](https://docs.flozu.app/guides/response-times-and-cost.md) it.

**Run by someone else.** A part another company runs, drawn with a dashed outline.

**Scenario.** A “what if?” played over time on a map, such as Black Friday.

**Single point of failure.** A part or zone that nothing takes over from, so traffic fails when it goes down. Fixed by a change to the map’s shape, such as a standby copy beside it. See [failure drills](https://docs.flozu.app/guides/failure-drills.md#fix-it).

**Spare room.** How much headroom a part should keep. A part past it is tight. 30% by default.

**Standby line.** A line that carries nothing until a line beside it fails, like a failover to a replica. See [lines](https://docs.flozu.app/guides/lines.md#standby-lines).

**Story.** A walk through a map, one step at a time, for presenting it.

**Tight.** Busier than its spare room allows, but not yet over its capacity.

**Uses line.** A dotted grey line saying one part depends on another, such as code using a library. It carries no traffic.

**Version.** The map as it was at one moment, kept beside it.

**Weak spot.** A part or zone the map can least afford to lose, found by taking each down in turn. See [failure drills](https://docs.flozu.app/guides/failure-drills.md#find-weak-spots).

**View.** One way of showing a map to one audience, with things hidden and plain wording.

**Zone.** A frame around parts that belong together, such as a region or a team. Called a group in the file format.