Which type of Variable do I need to use to change the Value of a text UI object ?

I am trying to display the Score of my player. I set up the reference to the Playermovement Script where the Scorecounting takes place and I converted the Score to a string type. I thought it would work like this but im getting the following error :
Assets/ScoreDisplay.cs(20,17): error CS0029: Cannot implicitly convert type string' to UnityEngine.UI.Text’
So I am assuming that string is not the right type.
could someone explain what i did wrong and give a Solution ?
Thanks
heres my Script :

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class ScoreDisplay : MonoBehaviour {

Text text;

private string score;

Playermovement playermovement;

void Start () {

	text = GetComponent<Text> ();

	playermovement = GetComponent<Playermovement> ();

}


void Update () {

	score = playermovement.playerscore.ToString();

	text = "Score:" + score;
}

}

(I am german. feel free to correct my english)

In your code you have this

Text text;
...
text = "Score:" + score;

You are attempting to store a variable of type string into a variable of type Text (unity UI text field) which is like trying to do int number = "Hello"

What you actually want to do is let the Text component know that you want it to display your string. To do that you would write

Text text;
...
text.text = "Score:" + score;

I recommend you rename you Text text variable to something like Text textLabel to avoid confusion. It is much more self explanatory to write textLabel.text = "Hello";