Updates in Unity 5.5

from: https://docs.unity3d.com/ScriptReference/MonoBehaviour.Update.html

Update  is called every frame, if the MonoBehaviour  is enabled. Update  is most commonly used function to implement any kind of game behaviour.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    void Update () {
        transform.Translate (0, 0, Time.deltaTime * 1);
    }
}

In order to get the elapsed time since the last call to Update , use Time.deltaTime . This function is only called if the Behaviour  is enabled. Override this function in order to provide your component’s functionality.

from: Unity 5.x By Example by Alan Thorn

In addition to the Update  function called on each frame, Unity also supports two other related functions, namely, FixedUpdate  and LateUpdate . FixedUpdate  is used when coding with Physics, and  is called a fixed number of times per frame. LateUpdate  is called once per frame for each active object, but the LateUpdate  call will always happen after every object has received an Update  event. Thus it happens after the Update  cycle, making it a late update.

from: https://docs.unity3d.com/ScriptReference/MonoBehaviour.FixedUpdate.html

This function is called every fixed framerate frame, if Monobehaviour  is enabled. FixedUpdate  should be used instead of Update  when dealing with Rigidbody . For example when adding a force to a rigidbody, you have to apply the force every fixed frame inside FixedUpdate  instead of every frame inside Update .

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    public Rigidbody rb;

    void Start () {
        rb= GetComponent<Rigidbody> ();
    }

    void FixedUpdate () {
        rb.AddForce (10.0f * Vector3.up);
    }
}