Text UI in Unity

TextController.cs

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // brings in UI information

public class TextController : MonoBehaviour {

	public Text text; // requires UnityEngine.UI, publicly exposes the text
	 
	// Use this for initialization
	void Start () {
		text.text = "Hello World";
	}
	
	// Update is called once per frame
	void Update () {
		if (Input.GetKeyDown (KeyCode.Space)){
		text.text = "Space key pressed";
		}
	}
}