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Select Mode is a specialized tool for speeding up and simplifying environment creation in Unreal Engine 5. Similar in nature to the Content Browser, Select Mode focuses only on Actors, that is, assets that can be directly placed within your level. While active, Select Mode gives you immediate access to all objects that you have placed within your Level.
Select Mode exists as a way to greatly speed up design times when placing and editing various props and other elements in your Level.
When Select Mode is active, after you drag an instance of an asset from the Place Actors panel (by default, located in the upper left corner of the main interface), you can immediately transform and edit Actors in the Level. See Placing Actors for other methods of placing Actors.