# Glossary

Platform terms, in alphabetical order, each linking to its full page.

## Application

One deployed project, linked to one repository (or created from an [upload](/create/upload) or [template](/create/templates)). Holds the settings its environments inherit. See [Deployments](/platform/deployments).

## Build

The step that turns a commit into something runnable: a folder of static files or a container image. Runs on Cloud Build. See [Builds](/platform/deployments/builds).

## Cold start

The seconds an app at zero instances takes to boot for its first request after idle. The price of [scale to zero](#scale-to-zero). See [Scaling](/create/scaling#cold-starts).

## Concurrency

How many requests one instance serves at the same time. Default 80, capped per [size](#size). See [Scaling](/create/scaling#concurrency).

## CPU target

The average CPU percentage at which autoscaling adds an instance. Default 80%. See [Scaling](/create/scaling#cpu-target).

## Deployment

One commit, built and released to one environment. Each environment keeps its last 20. See [Deploy history](/platform/deployments#deploy-history).

## Detection

Light Cloud reading a repository to work out the framework, package manager, build command, and output directory. See [How detection works](/platform/frameworks#how-detection-works).

## Environment

One running copy of an application, with its own URL, settings, and variables. One per connected branch: one production, the rest [previews](#preview-environment). See [How it works](/getting-started/how-it-works#applications-and-environments).

## Environment variable

A configuration value or secret set on an application or environment, delivered at build time (static) or runtime (container). See [Environment variables](/platform/environment-variables).

## Instance

One running copy of a container app. Autoscaling adds and removes instances between the [min](/create/scaling#min-instances) and [max](/create/scaling#max-instances). Billed per instance-hour.

## Output directory

The folder a static build writes the finished site into - exactly what the CDN serves. See [Build settings](/create/build-settings#output-directory).

## Point-in-time recovery

Restoring a PostgreSQL database to a chosen moment rather than to the last daily backup. See [Backups](/platform/databases/backups).

## Preview environment

An environment created for a branch, at its own URL, removed when the branch is deleted. See [Preview environments](/platform/preview-environments).

## Production environment

The protected environment deployed from the production branch (`main` or `master` by default). Cleanup never touches it. See [Deployments](/platform/deployments#the-production-environment).

## Region

The data centre a container app or database runs in. Tier-1 regions bill at base rates; tier-2 (coming) carry a surcharge. See [Application settings](/create/application-settings#region).

## Root directory

The folder of a monorepo an application builds from. Pushes elsewhere in the repo don't rebuild it. See [Application settings](/create/application-settings#root-directory).

## Scale to zero

An app with min instances 0 sleeping when idle - and not billing while asleep. See [Billing](/billing/billing#scale-to-zero).

## Shared tier

The pooled database tier: your own credentials and database on a shared instance, ready in seconds, about $3 a month. See [Databases](/platform/databases#the-shared-tier).

## Size

The vCPU and memory of each instance, Nano through Large. See [Application settings](/create/application-settings#size).

## Stack

A template that creates an application and a connected database in one go - WordPress, Open SaaS. See [Templates](/create/templates#stacks).

## Static site

A build served entirely from the CDN: no server, no region, no cold starts, free bandwidth. See [Frameworks](/platform/frameworks#frontend).