The number data type is used to represent numeric data. For a full description, please visit the Numeric Data Type page.
The string data type is used to represent character data. For a full description, please visit the String Data Type page.
The logical (or boolean) data type is used to represent true/false data. For a full description, please visit the Logical Data Type page.
The null data type is a special case. It represents no data--not an empty string, not zero, but literally nothing.
Composite Data (Arrays, Dates, etc.)
For a description of composite data types, please visit the Object Reference page.