Understanding roblox studio local script vs server script is basically the first real "aha!" moment you have as a developer. If you've ever tried to make a button that opens a menu, or a sword that actually deals damage, and wondered why it works for you but not for anyone else—or why it doesn't work at all—you've bumped into the wall between the client and the server. It's the single most important concept in Roblox development, and honestly, once you wrap your head around it, everything else starts to click.
Let's be real: when you first open Roblox Studio, seeing "Script" and "LocalScript" in the menu is confusing. They both use Luau, they both look the same in the editor, but they live in totally different worlds. If you use the wrong one, your game is either going to be a buggy mess or a playground for exploiters. So, let's break down exactly what the difference is, where they live, and when you should reach for one over the other.
The Big Picture: Client vs. Server
To understand the difference, you have to think about how an online game actually works. Roblox isn't just running on your computer; it's a conversation between your computer (the Client) and a powerful computer far away (the Server).
The Server is the boss. It's the ultimate authority. It keeps track of the "truth" of the game. If the server says a player has 100 health, then they have 100 health, no matter what the player's computer thinks.
The Client is the player's individual experience. It handles what they see, what they hear, and what buttons they're pressing. It's the "rendering" side of things.
When we talk about roblox studio local script vs server script, we're really talking about which side of this conversation we're writing for.
What is a Server Script?
In Roblox Studio, a regular "Script" (with the white scroll icon) is a server-side script. This script runs on the Roblox servers. Because it's running on the server, it has the power to change things for everyone in the game.
If a server script changes the color of a brick to red, every single player in the game will see that brick turn red. If a server script gives a player a "Gold" badge, that change is saved to their profile across the whole platform.
Where do they live?
You'll usually put these in ServerScriptService. This is a safe place where the player's computer can't even see the code, which makes it great for security. You can also put them in the Workspace if they need to be inside a specific part or model.
Use cases for Server Scripts:
- Saving Data: Anything involving DataStores must happen on the server.
- Giving Rewards: If you're giving players currency or items, the server has to do it so people can't just "cheat" items into their inventory.
- Game Logic: Managing round timers, spawning players, or deciding who won a match.
- Health and Combat: Dealing damage to enemies or other players.
What is a Local Script?
A LocalScript (the one with the blue person icon) runs on the client. Specifically, it runs on the computer or phone of the person playing the game. This means its power is limited. If a LocalScript changes a brick to blue, only that one player sees it. For everyone else, the brick stays the original color.
This sounds like a limitation, but it's actually vital. You don't want the server handling every tiny mouse movement or UI animation; that would be incredibly laggy.
Where do they live?
LocalScripts won't run just anywhere. They need to be "connected" to a player. Common spots include: * StarterGui: For all your menus, buttons, and HUDs. * StarterPlayerScripts: For things like custom camera controls or keyboard inputs. * StarterCharacterScripts: For things that happen to the player's physical body (like a custom walk sound). * Inside a Tool: So the script runs when the player equips the item.
Use cases for Local Scripts:
- User Interface (UI): Opening a shop menu, updating a stamina bar, or showing a notification.
- Input: Detecting when someone presses "E" to interact or clicks their mouse.
- Camera: Making the camera shake or zooming it in during a cutscene.
- Visual Effects: Things that are just for "eye candy" and don't affect the actual gameplay logic.
Why Can't We Just Use One?
You might be thinking, "Why not just do everything on the server?" Well, the main reason is latency (or lag).
Imagine you're playing a fast-paced shooter. Every time you move your mouse, the computer has to send a message to a server in Virginia, wait for the server to process it, and send a message back saying "Okay, turn the camera." You'd feel a massive delay. It would be unplayable. LocalScripts allow the game to feel snappy because the player's computer handles the immediate feedback.
On the flip side, why not do everything on the local script? One word: Exploiters. If you let a LocalScript decide how much money a player has, a hacker could just open a cheat program, change a single line of code, and give themselves a billion coins. The server wouldn't know any better. This is why we have Filtering Enabled (the default state of Roblox), which basically means "The server doesn't trust anything the client says unless it's been double-checked."
The Bridge: RemoteEvents
So, if the client handles the "input" and the server handles the "truth," how do they talk to each other? This is where RemoteEvents come in.
Think of a RemoteEvent like a walkie-talkie. A LocalScript can say, "Hey Server, I just clicked the 'Buy' button for this sword." The server then receives that message, checks if the player actually has enough money, and if they do, it gives them the sword.
When people compare roblox studio local script vs server script, they often forget that most features actually require both working together through a RemoteEvent.
Common Mistakes Beginners Make
One of the most common facepalm moments for new devs is trying to play a sound or change a GUI from a server script. While the server can technically do some of this, it's usually better to let the client handle it.
Another big one is trying to detect a mouse click (like Mouse.Button1Down) inside a server script. It won't work! The server doesn't have a mouse. It doesn't have a screen. It's just a box in a data center. Only a LocalScript can "see" what the player is doing with their mouse or keyboard.
Also, watch out for where you put your scripts. If you put a LocalScript into ServerScriptService, it will sit there and do absolutely nothing. It's like trying to run a Windows app on a toaster—it's just not the right environment.
Which One Should You Use? A Quick Cheat Sheet
If you're still staring at the "Insert Object" menu wondering which one to pick, ask yourself these three questions:
- Does this need to be secure? (Money, XP, Ranks) -> Server Script.
- Is this just for the player to see? (Menus, UI, Camera effects) -> Local Script.
- Does it need to happen for everyone at once? (A giant explosion in the middle of the map) -> Server Script.
If the answer is "The player does something that needs to affect everyone else," then you need a LocalScript to catch the input and a RemoteEvent to tell a Server Script to make the change.
Final Thoughts
The debate of roblox studio local script vs server script isn't really a competition—it's about teamwork. You're building an ecosystem where the client handles the "feel" and the server handles the "rules."
It takes a bit of practice to get used to thinking in this "split-brain" way, but once you do, you'll be able to build much more complex and secure games. Next time you're about to script a feature, just take a second to think: "Whose job is this? The boss (Server) or the person on the ground (Client)?" Your game—and your players—will thank you for it.
Happy devving! Keep experimenting, and don't be afraid to break things. That's usually how the best learning happens anyway.