When you first dive into game development, understanding the roblox local script vs server script divide is usually the first major hurdle you'll hit. It's that confusing moment where you write a perfectly good piece of code to change a part's color, but then you realize your friends can't see the change, or worse, your script doesn't run at all. This distinction is the backbone of how Roblox works, and honestly, once you wrap your head around it, the rest of your scripting journey gets a whole lot smoother.
Think of it like a multiplayer party. The "Server" is the host's house—everyone is there, and the host decides what's actually happening. The "Local" side is your own personal pair of sunglasses. You can put them on and see the world in a different tint, but that doesn't mean everyone else's world has changed. In Roblox terms, if you don't know where to put your code, you're going to have a very lonely game where nothing works the way it should.
The Server Script: The Source of Truth
In Roblox Studio, when you just see an object named "Script," that's your server-side script. This is the heavy lifter. It runs on Roblox's cloud servers, not on your computer. Because of that, anything a server script does is "canonical." If a server script deletes a wall, that wall is gone for every single player in the game.
You'll mostly use server scripts for things that need to be "official." If you're making a leaderboard, you want the server to handle the math. If you're saving a player's data (like how much gold they have), you definitely want the server doing that. Why? Because you can't trust the player's computer. If the player's computer decided how much gold they had, someone would just write a tiny bit of code to give themselves a billion coins in three seconds.
Server scripts usually live in ServerScriptService or inside objects in the Workspace. They are the "referees" of your game, making sure the rules are followed and that everyone sees the same reality.
The Local Script: The Player's Perspective
Now, the roblox local script vs server script debate gets interesting when we talk about responsiveness. A LocalScript runs on the player's actual device—their phone, laptop, or console. Because it's running locally, it's incredibly fast. There's no "lag" between the player clicking a button and the code running.
Local scripts are mostly used for things that only one player needs to experience. This includes things like: * User Interface (GUI): When a player opens their inventory, nobody else needs to see that menu pop up on their screen. * Input Handling: Detecting when someone presses the "W" key or clicks their mouse. * Camera Movements: Every player has their own camera. If you want to make the screen shake during an explosion, that's a job for a local script. * Local Effects: Maybe you want a special particle effect to follow the player around, but it's too heavy for the server to calculate for 50 people. You can make it happen locally.
The catch? If a LocalScript changes something in the game world, like moving a part, the server won't know about it. To the server (and every other player), that part is still sitting in its original spot. This is what we call "Client-Side" vs "Server-Side."
Why the Distinction Matters for Security
Back in the day, Roblox was a bit more like the Wild West. You could change things locally and they might replicate to the server. But today, we have something called FilteringEnabled. This is a security feature that essentially puts a big wall between the client (local) and the server.
If you're wondering about roblox local script vs server script security, the rule of thumb is: Never trust the client. Exploiter programs work by injecting code into the local side of the game. They can change their walk speed, make themselves fly, or delete parts on their own screen. But because of FilteringEnabled, those changes stay local. They aren't "real" to the rest of the players.
As a developer, you have to design your game with this in mind. You can't have a "Buy" button in a local script that just tells the server "I bought this, give it to me." You need a way for the two sides to talk securely.
The Bridge: RemoteEvents and RemoteFunctions
Since the server and the local script are basically living in two different worlds, they need a way to communicate. This is where RemoteEvents come in. Think of a RemoteEvent like a walkie-talkie.
Let's say a player clicks a "Heal" button on their screen. 1. A LocalScript detects the mouse click. 2. The LocalScript "fires" a RemoteEvent to the server saying, "Hey, Player 1 wants to heal." 3. A ServerScript listens for that event. It checks if the player actually has a health potion. 4. If they do, the ServerScript adds 20 HP to the player's health.
This setup ensures that the player can't just "fake" the healing. The server does the verification. Mastering the relationship between roblox local script vs server script is mostly about mastering how and when to use these RemoteEvents.
Where Do These Scripts Live?
This is a common point of frustration for beginners. You can't just put a LocalScript anywhere and expect it to work.
- LocalScripts only run if they are descendants of:
- The player's
Backpack(like inside a Tool) - The player's
Charactermodel PlayerGuiPlayerScriptsReplicatedFirst
- The player's
If you put a LocalScript inside the Workspace (unless it's in a Tool the player is holding), it usually won't do anything. It'll just sit there.
- Server Scripts (regular Scripts), on the other hand, will run in the
WorkspaceorServerScriptService. However, they won't run if you put them insideReplicatedStorageorStarterGui(until they are cloned into a player's folder).
Common Mistakes and How to Avoid Them
One of the most frequent mistakes is trying to handle player input in a server script. You might try to detect a keypress inside a regular script, and it simply won't work because the server doesn't have a keyboard—the player does!
Another classic is the "invisible change." You might use a LocalScript to change the game's time of day to night, thinking it looks cool, but then you realize all your players are walking around in broad daylight while you're the only one in the dark. If you want everyone to see the change, the server has to be the one to make the call.
Also, don't overcomplicate things. I've seen people try to use RemoteEvents for every tiny movement, like a door swinging open. While you could do that, sometimes it's better to let the server handle the door's physical state so that it stays consistent for everyone. If you do it locally, one person might walk through an open door while another person sees it as closed and gets stuck walking into a wall.
Which One Should You Use?
When you're staring at that "New Script" button, ask yourself: "Does this affect everyone, or just the person doing it?"
If you're writing code for a sword, you'll actually use both. A LocalScript will detect when the player clicks their mouse to swing the sword (so it feels instant). That LocalScript then tells a RemoteEvent to fire. A ServerScript then picks up that signal, plays the "swing" animation for everyone else to see, and checks if the sword hit an enemy to deal damage.
It sounds like more work to use two scripts instead of one, but that's the secret sauce of a well-made Roblox game. It keeps things fast for the player but secure and synchronized for the server.
Wrapping Up the Local vs Server Logic
At the end of the day, the roblox local script vs server script relationship is about balance. You want your game to feel "snappy" and responsive, which means putting your visual effects and UI logic in local scripts. But you also want your game to be fair and functional, which means keeping your game logic, data saving, and physics "truth" on the server.
Don't be discouraged if you get them mixed up at first. We've all been there—wondering why a LocalScript inside ServerStorage isn't firing, or why a server-side change isn't showing up instantly on a laggy connection. Just remember the "Sunglasses vs. House" analogy. The server is the house everyone shares; the local script is just what you're seeing through your own lenses. Once you get that down, you're well on your way to making something awesome.