# Yield instruction reference > Yield different custom instructions in your coroutine methods to control when they resume. Coroutines suspend their execution at a `yield return` statement. A `yield return null` suspends execution of the coroutine until the next frame. But the `yield return` can also return an instruction for the Unity Editor or runtime to, for example, wait for a specified amount of time or until a condition is met before resuming execution of the coroutine. ## Runtime yield instructions Unity has a set of custom yield instructions derived from [`UnityEngine.YieldInstruction`](/engine/6000.3/script-reference/unityengine/yieldinstruction.md) that you can use to resume after a specified time, when a specified conditions is met, or at specific points in the Player loop. | Instruction | Description | | ------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [`AsyncOperation`](/engine/6000.3/script-reference/unityengine/asyncoperation.md) | Suspends a coroutine and resumes when an asynchronous operation completes, such as loading a scene or asset. | | [`WaitForEndOfFrame`](/engine/6000.3/script-reference/unityengine/waitforendofframe.md) | Suspends a coroutine and resumes at the end of the frame, after all rendering and GUI events.**Note**: `WaitForEndOfFrame` never runs in Edit mode when the Editor is in batch mode, even if scripts are marked with `[ExecuteInEditMode]` or `[ExecuteAlways]`. | | [`WaitForFixedUpdate`](/engine/6000.3/script-reference/unityengine/waitforfixedupdate.md) | Suspends a coroutine and resumes at the end of the next physics update, after all physics calculations. | | [`WaitForSeconds`](/engine/6000.3/script-reference/unityengine/waitforseconds.md) | Suspends a coroutine and resumes after a specified number of seconds, taking the time scale into account. | | [`WaitForSecondsRealtime`](/engine/6000.3/script-reference/unityengine/waitforsecondsrealtime.md) | Suspends a coroutine and resumes after a specified number of seconds, ignoring the time scale. | | [`WaitUntil`](/engine/6000.3/script-reference/unityengine/waituntil.md) | Suspends a coroutine and resumes when a supplied delegate evaluates to `true`. | | [`WaitWhile`](/engine/6000.3/script-reference/unityengine/waitwhile.md) | Suspends a coroutine and resumes when a supplied delegate evaluates to `false`. | For more information and example usage of these yield instructions, refer to their API reference pages. For a visual representation of where different coroutines resume in the Player loop, refer to the diagram in [Event function execution order](/engine/6000.3/manual/scripting/object-oriented-development/managing-update-order/execution-order.md). ## UnityTest yield instructions Unity Test Framework tests marked with the `[UnityTest]` attribute run as coroutines. The Test Framework package adds support for additional yield instructions to control the Unity Editor from tests and provides the possibility to define custom yield instructions. | Instruction | Description | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------- | | [`EnterPlayMode`](https://docs.unity3d.com/Packages/com.unity.test-framework@latest/index.html?subfolder=/api/UnityEngine.TestTools.EnterPlayMode.html) | Creates a yield instruction for the Unity Editor to enter Play mode. | | [`ExitPlayMode`](https://docs.unity3d.com/Packages/com.unity.test-framework@latest/index.html?subfolder=/api/UnityEngine.TestTools.ExitPlayMode.html) | Creates a yield instruction for the Unity Editor to exit Play mode. | | [`RecompileScripts`](https://docs.unity3d.com/Packages/com.unity.test-framework@latest/index.html?subfolder=/api/UnityEngine.TestTools.RecompileScripts.html) | Triggers a recompilation of scripts in the Unity Editor. | | [`WaitForDomainReload`](https://docs.unity3d.com/Packages/com.unity.test-framework@latest/index.html?subfolder=/api/UnityEngine.TestTools.WaitForDomainReload.html) | Delays the execution of scripts until after an incoming domain reload. | For more information on the yield instructions provided by Unity Test Framework, refer to [Yield instructions for the Editor](/engine/6000.3/manual/scripting/test-framework-introduction/writing-tests/reference-custom-yield-instructions.md). ## Editor yield instructions The Editor coroutines package adds support for coroutines that run in the Unity Editor's Edit mode. The package includes additional yield instructions for Edit mode coroutines. | Instruction | Description | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------- | | [`EditorWaitForSeconds`](https://docs.unity3d.com/Packages/com.unity.editorcoroutines@latest/index.html?subfolder=/api/Unity.EditorCoroutines.Editor.EditorWaitForSeconds.html) | Resumes an EditorCoroutine after a specified number of seconds, taking the time scale into account. | For more information, refer to [Editor coroutines](https://docs.unity3d.com/Packages/com.unity.editorcoroutines@latest). ## Batch mode support All runtime coroutine yield instructions run as normal when you run a standalone [Player in batch mode](/engine/6000.3/manual/unity-editor/command-line-arguments/player.md). If you run the [Editor in batch mode](/engine/6000.3/manual/unity-editor/command-line-arguments/editor.md#batchmode) and your project has scripts marked with [`[ExecuteInEditMode]`](/engine/6000.3/script-reference/unityengine/executeineditmode.md) or [`[ExecuteAlways]`](/engine/6000.3/script-reference/unityengine/executealways.md) so that they also run in Edit mode, all runtime coroutines in those scripts run in Edit mode except for `WaitForEndOfFrame`. This is because not all Unity subsystems update as regularly in Edit mode as they do at runtime. For more information, refer to the [`[ExecuteAlways]`](/engine/6000.3/script-reference/unityengine/executealways.md) API reference. ## Additional resources * [Command-line arguments](/engine/6000.3/manual/unity-editor/command-line-arguments.md) * [`[ExecuteAlways]`](/engine/6000.3/script-reference/unityengine/executealways.md) API reference