runService

RunService is a core Roblox service that exposes the engine’s update loop to scripts. It enables code to run in sync with the physics simulation, frame rendering, and the overall game loop. The service is accessed with game:GetService("RunService"), and its behavior can differ between server, client, and Studio contexts.

The service provides several events used to hook into the engine cycle. Stepped fires before each physics step and runs on both the server and client; RenderStepped runs only on the client and fires before rendering each frame; Heartbeat fires every frame and is often used for high-frequency updates that don’t rely on rendering. Each of these events passes a delta time value indicating the elapsed time since the last firing, allowing scripts to scale movement and other time-dependent logic.

In addition to events, RunService offers binding capabilities. BindToRenderStep enables registering a function to a named render step on the client with a specified priority, allowing precise control over the order of render-related tasks. BindToClose registers callbacks to run as the game is shutting down, providing a chance for cleanup.

Environment checks are supported via methods such as RunService:IsServer(), RunService:IsClient(), and RunService:IsStudio(), which help scripts tailor behavior to the current environment.

Usage guidance. RenderStepped is typically used for client-side visuals and camera updates, Stepped for physics- or time-step logic, and Heartbeat for low-latency, per-frame updates not tied to rendering. Developers should keep callbacks lightweight to avoid frame drops and use appropriate step types to maintain smooth performance.