Luau reference

The language you’re learning

Luau is the scripting language used in Roblox. It grew from Lua 5.1 and adds its own features, including gradual types. These activities teach Luau consistently.

Values, names, and conditions

local level = 5 -- assignment
local allowed = level >= 5 -- comparison
local message = "Level " .. level -- concatenation
local hasPass = false
if allowed or hasPass then
    print(message)
end

Names are case-sensitive. Assignment uses =; equality comparison uses ==. Arithmetic combines numbers; .. joins strings. nil means no value, while false is a boolean. Only nil and false are false in conditions: zero is truthy.

Functions and tables

local function label(name)
    return "Hello, " .. name
end
local items = { "Lamp", "Gate" }
print(items[1]) -- sequence indices start at 1
local copy = table.clone(items) -- shallow copy

A local name is visible in its enclosing scope after its declaration; it does not become a shared global. Two equal-looking tables are different identities. Assigning one table to another name shares that identity. table.clone copies one level; nested mutable values still need explicit copying.

Types help describe intent

local function greeting(name: string): string
    return "Welcome, " .. name
end
local function safeName(value: unknown): string
    if type(value) == "string" then
        return value
    end
    return "Visitor"
end

Type annotations and refinements help tooling reason about code. This browser executes Luau syntax; it does not provide Roblox Studio’s script analysis or engine autocomplete.

Browser runtime and Studio

Runs here means a genuine, pinned Luau runtime in a disposable browser worker. Learning simulation previews use evaluated values, with no Roblox physics, services, Instances, or replication. Requires Roblox Studio means you create and test the described hierarchy in your own isolated practice place.

Server assessment compiles source in a separate restricted runner. When it is unavailable, the site preserves your draft and shows the limitation; a browser result cannot grant trusted completion.

Authoritative multiplayer state

A LocalScript cannot be trusted to decide rewards. The server validates input, permissions, distance, timing, and duplicate claims using its own state. UI feedback belongs on the client; authority belongs on the server.

Learning and privacy

Lesson attempts and private code stay private. Learning XP is separate from community XP. A learning milestone describes an activity, not official Roblox accreditation or proof of professional quality. You can export or delete private code from My Journey.