If you've been messing around in Studio for more than a few days, you've probably realized that a simple roblox remote function script is basically the backbone of any game that actually needs to talk back and forth between the player and the server. It's one of those things that feels a bit confusing at first, especially when you're trying to figure out why your code is hanging or why the server isn't responding, but once it clicks, it changes everything about how you build your game's logic.
Most people start out using RemoteEvents, which are great for "fire and forget" messages. You tell the server to do something, and you don't really care when it finishes. But a RemoteFunction is a different beast entirely. It's a two-way street. You're not just sending a message; you're asking a question and waiting for an answer.
How the two-way communication works
Think of a RemoteEvent like a text message. You send it, put your phone down, and go about your day. A roblox remote function script, on the other hand, is more like a phone call. You ask the person on the other end for some information, and you stay on the line until they give it to you. In technical terms, we call this "yielding." Your script stops right at the line where you called the function and waits patiently for the return value.
This is super useful for things like shop systems. Imagine a player wants to buy a new sword. The client (the player's computer) can't just decide they bought it—that would be a huge security risk because hackers could just tell the game they have a billion coins. Instead, the client uses a RemoteFunction to ask the server: "Hey, can I afford this?" The server checks the database, subtracts the money if they have enough, and then sends back a "True" or "False" to the client.
Setting up your first script
To get started, you'll want to head over to ReplicatedStorage in your Explorer window. This is the common ground where both the server and the client can see things. Right-click, insert a RemoteFunction, and give it a name like GetPlayerData or ProcessPurchase.
Now, you need two separate scripts to make this work. One will live on the server (usually in ServerScriptService), and the other will be a LocalScript (usually in StarterPlayerScripts or inside a GUI).
On the server side, you'll define what happens when that function is called. You use the .OnServerInvoke callback. It looks something like this:
```lua local ReplicatedStorage = game:GetService("ReplicatedStorage") local myRemoteFunction = ReplicatedStorage:WaitForChild("MyRemoteFunction")
myRemoteFunction.OnServerInvoke = function(player, requestType) print(player.Name .. " is asking for " .. requestType)
if requestType == "Coins" then return 100 -- Just a placeholder for actual data end return "Unknown request" end ```
On the client side, you call it using :InvokeServer(). Remember, because this yields, you want to make sure you aren't calling it in a way that freezes your entire UI if the server takes a second to respond.
Why yielding can be a double-edged sword
The fact that a roblox remote function script waits for a response is its best feature, but also its biggest danger. If the server-side script hits an error or gets stuck in an infinite loop, the client-side script that called it will wait and wait and wait. This is what we call an "infinite yield."
If your LocalScript is waiting forever, the player might find that their buttons stop working or their game feels like it has crashed. This is why you have to be really careful with your server-side logic. You always want to make sure your function eventually returns something, even if it's just a "nil" value or an error message.
One way to handle this is by wrapping your invocation in a pcall (protected call). This prevents the entire script from breaking if something goes wrong during the communication. It's just a good habit to get into once your game starts getting complex.
Security is not optional
Let's talk about the "trust no one" rule of Roblox development. When you're writing a roblox remote function script, you have to assume that a malicious player will try to send garbage data to your server.
The first argument of .OnServerInvoke is always the player who called it. Roblox handles this automatically, so a hacker can't pretend to be someone else easily. However, they can change any other arguments you send. If your function is BuyItem(price), a hacker could manually call that function through a cheat engine and pass -999999 as the price.
If your server script just takes that number and adds it to their balance, you've just given them infinite money. Always validate everything on the server. The server should be the "source of truth." It should check its own records for how much an item costs, rather than trusting the number the client sent over.
When should you use an event instead?
It's tempting to use RemoteFunctions for everything because getting a return value is so convenient. But they aren't always the right choice. Since they yield, they are inherently slower and more resource-intensive than RemoteEvents.
If you don't actually need a piece of data back right this second, use a RemoteEvent. For example, if a player clicks a "Save Game" button, you can just fire an event. The server will start saving, and the player doesn't need to wait for a "Success" message to keep playing the game. You only use the roblox remote function script when the next step of your client-side code absolutely depends on the result of the server's calculation.
Common mistakes and how to fix them
One of the most frequent errors I see is people trying to use .OnClientInvoke. While it exists, it's generally considered a bad idea. This allows the server to ask the client for information. Why is this bad? Because if a player is laggy or using a modified client, they can simply refuse to answer the server's "call."
If your server script is waiting for a response from a client and that player's internet dies, your server script might hang indefinitely. This can cause major issues for your game's performance. It's almost always better to have the client push information to the server or have the server just tell the client what to do without waiting for a reply.
Another mistake is forgetting that InvokeServer is synchronous. If you put it inside a loop that needs to run fast (like a RenderStepped connection), you're going to see massive frame drops. Always keep your remote calls as efficient as possible.
Wrapping it up
Mastering the roblox remote function script is really about understanding the flow of data. Once you get comfortable with the idea of the client asking a question and the server providing the answer, you can build much more robust systems. Whether it's fetching a player's inventory, checking permissions, or calculating complex math that you don't want the client to see, RemoteFunctions are the way to go.
Just keep that security mindset. Don't trust the client, handle your errors with care, and don't let your scripts yield into oblivion. If you stick to those rules, your game logic will be way more stable and much harder for exploiters to mess with. Happy scripting, and don't be afraid to experiment with how you structure your calls—it's the best way to learn what works for your specific game.