Scripting Reference
Resources.Load

static function Load (path : String) : Object

Description

Loads an asset stored at path in a Resources folder.

Returns the asset at path if it can be found otherwise returns null. The path is relative to any Resources folder inside the Assets folder of your project, extensions must be omitted.

JavaScript 
    // Assigns a texture named "Assets/Resources/glass" to a Plane.
    function Start () {
        var go = new GameObject.CreatePrimitive(PrimitiveType.Plane);
        go.renderer.material.mainTexture = Resources.Load("glass") as Texture;
    }
using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Start() {
        GameObject go = GameObject.CreatePrimitive(PrimitiveType.Plane);
        go.renderer.material.mainTexture = Resources.Load("glass") as Texture;
    }
}
import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Start():
        go as GameObject = GameObject.CreatePrimitive(PrimitiveType.Plane)
        go.renderer.material.mainTexture = (Resources.Load('glass') as Texture)
Another example:
JavaScript 
    // Instantiates a prefab at the path "Assets/Resources/enemy".
    function Start () {
        var instance : GameObject = Instantiate(Resources.Load("enemy"));
    }
using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Start() {
        GameObject instance = Instantiate(Resources.Load("enemy"));
    }
}
import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Start():
        instance as GameObject = Instantiate(Resources.Load('enemy'))

static function Load (path : String, systemTypeInstance : Type) : Object

Description

Loads an asset stored at path in a Resources folder.

Returns the asset at path if it can be found otherwise returns null. Only objects of type will be returned. The path is relative to any Resources folder inside the Assets folder of your project, extensions must be omitted.

JavaScript 
    // Assigns a texture named "glass" to a Plane.
    function Start () {
        var go = new GameObject.CreatePrimitive(PrimitiveType.Cube);
        go.renderer.material.mainTexture = Resources.Load("glass", Texture2D);
    }
using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Start() {
        GameObject go = GameObject.CreatePrimitive(PrimitiveType.Cube);
        go.renderer.material.mainTexture = Resources.Load("glass", typeof(Texture2D));
    }
}
import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Start():
        go as GameObject = GameObject.CreatePrimitive(PrimitiveType.Cube)
        go.renderer.material.mainTexture = Resources.Load('glass', Texture2D)
JavaScript 
    // Instantiates a prefab named "enemy" located in any Resources
    // folder in your project's Assets folder.
    function Start () {
        var instance : GameObject = Instantiate(Resources.Load("enemy", GameObject));
    }
using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Start() {
        GameObject instance = Instantiate(Resources.Load("enemy", typeof(GameObject)));
    }
}
import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Start():
        instance as GameObject = Instantiate(Resources.Load('enemy', GameObject))