Input.GetAxisRaw

Description

Returns the value of the virtual axis identified by axisName with no smoothing filtering applied.

The value will be in the range -1...1 for keyboard and joystick input. Since input is not smoothed, keyboard input will always be either -1, 0 or 1. This is useful if you want to do all smoothing of keyboard input processing yourself.

function Update () {
    var speed : float = Input.GetAxisRaw("Horizontal") * Time.deltaTime;
    transform.Rotate (0, speed, 0);
}

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    void Update()
    {
        float speed = Input.GetAxisRaw("Horizontal") * Time.deltaTime;
        transform.Rotate(0, speed, 0);
    }
}

The GetAxis page describes in detail what the axisName for GetAxisRaw means. For example the Horizontal axis is managed by Left and Right, and a and d keys. Other Input Axes can be seen in the Edit->Settings->Input window.