The Explorer window uses the concept of parenting to organize all of the instances hierarchically. If an instance has any children, it will show a small arrow next to its name. Clicking on this arrow toggles a list of all the children of that instance.
At the base level, the Explorer is organized into several categories and services.
|Category / Service||Description|
|Workspace||Contains all of the visible objects in the Place. If you want a Part or Model to appear in the game and be affected by the game's physics and other systems, it should be in here.|
|Players||Contains all of the players currently in the place.|
|Lighting||Controls various settings related to lighting.|
|ReplicatedFirst||Replicates all of its contents to the player client before anything else is replicated. Useful for loading screens.|
|ReplicatedStorage||A storage service whose contents are accessible to the server and clients.|
|ServerScriptService||Stores and runs server-side scripts in your place. Any active script inside this service will automatically run when the place starts. Contents are not replicated to clients.|
|ServerStorage||Stores instances on the server without replicating to the client.|
|StarterGui||Stores GUI elements which are replicated to a player's PlayerGui when the player joins the place or respawns.|
|StarterPack||Stores tools and scripts which are replicated to a player's backpack when the player joins the place or respawns.|
|StarterPlayer||Controls various player settings and LocalScripts that run when the player first joins the game.|
|SoundService||Controls various settings related to audio.|
|Chat||Special service that houses all of the Lua code responsible for running Roblox's in-game chat.|
|LocalizationService||The service which is responsible for handling automated language translations.|