Variable

Naming

• Start with a “$”
• Can contain letters, numbers, and underscores
• Must start with letter or underscore and by convention should start with a lower case letter or underscore
• Case-sensitive

Referencing
• Variables can be assigned by value or by reference
• The ampersand (&) creates a reference, or alias, and causes both the original variable and alias to point to the same memory value

Initializing

• Variable typing is set automatically by the php parser and called “type juggling/coercion”
• Initializing variables empty is a good practice if it is possible it already points to memory values and you want to start empty
• The function isset() returns a boolean on a passed variable containing a value other than null string, null, or zero

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