MachinePrecision

MachinePrecision is a symbol used to indicate machine-number precision.

Examples

Request machine precision in numerical functions:

N[Pi, MachinePrecision]

Check the precision of a number:

Precision[1.5]
(* MachinePrecision *)

Use in NDSolve:

NDSolve[{y'[x] == y[x], y[0] == 1}, y, {x, 0, 1}, 
  WorkingPrecision -> MachinePrecision]

Please visit the official Wolfram Language Reference for more details.