What Is a Value?

A value is a piece of data that a program works with. In Lua, everything you store or manipulate is a value.

Examples of values:

• 10
• "hello"
• true
• nil

Values have a type, which tells Lua how to treat them.

Basic Value Types in Lua

Lua has a small number of core types:

• Number – numeric values (integers and decimals)
• String – text enclosed in quotes
• Boolean – logical values: true or false
• Nil – represents “no value”
• Table – collections of values (covered in detail later)
• Function – executable values (covered later)

For now, we focus on the first four.

Numbers

Numbers represent quantities and can be used in calculations.

Examples:

• 5
• 3.1
• -20

Common arithmetic operators:

• • addition
• • subtraction
• • multiplication
• / division
• % remainder

Lua treats all numbers as the same numeric type.

Strings

Strings represent text. They are written using:

• Double quotes: "Hello"
• Single quotes: 'Hello'

Strings can contain letters, numbers, and symbols.

Common string operations:

• Concatenation using ..
• Length using #

Strings are immutable, meaning they cannot be changed in place.

Booleans

Booleans represent truth values:

• true
• false

They are mainly used in conditions and logic.

Important rule: Only false and nil are considered false. Everything else is considered true.

Nil

nil represents the absence of a value. Uses of nil:

• Indicating that something does not exist
• Removing values from tables
• Representing “unknown” or “not set”

Accessing an undefined variable results in nil.

What Is a Variable?

A variable is a name that refers to a value. In Lua, variables are created by assignment.

Example:

x = 10
name = "Lua"

Assigning and Reassigning Variables

Variables can be reassigned to new values at any time. Example:

score = 100
score = 150

Local and Global Variables

Variables are either global or local. Global variables are accessible everywhere Local variables exist only within a limited scope

Example:

local count = 5

Using local is recommended to avoid unintended side effects.

Naming Rules and Conventions

Variable names:

• Can contain letters, numbers, and underscores
• Must not start with a number
• Are case-sensitive

Common conventions:

• snake_case for variables
• Descriptive names over short ones