A fundamental data type that holds double-precision floating-point numbers in IEEE format. A Double variable is stored as a 64-bit (8-byte) number ranging in value from -1.79769313486231E308 to -4.94065645841247E-324 for negative values, from 4.94065645841247E-324 to 1.79769313486231E308 for positive values, and 0.