The first data type I'll introduce you to is the integer. The integer is the fundamental numeric data type in PHP and represents whole-number signed values up to a little over 2 billion. In practice, PHP will accept integer values using three mathematical bases: decimal (base 10), octal (base 8), and hexadecimal (base 16). In most situations, PHP scripts are written using decimal notation; however, in some situations octal or hexadecimal numbers make life easier.