A variable is a box that stores a value. In PHP, its name always starts with the $ sign, for example $firstname = “Marie”;.

The main types

• String: text between quotes, e.g. “Hello”.
• Integer (int): a whole number, e.g. 42.
• Float: a decimal number, e.g. 3.14.
• Boolean (bool): true or false.
• Array: a list of values.

PHP works out the type on its own from the value you give: there is no need to declare it. This is called dynamic typing.

Displaying a variable

You can concatenate with a dot: echo “Hello ” . $firstname;. With double quotes, the variable is even read directly: echo “Hello $firstname”;.

Key point: a variable starts with $, stores a value, and PHP infers its type automatically.