Debug.Log
static function Log(message: object): void;
static void Log(object message);
static def Log(message as object) as void
static function Log(message: object, context: Object): void;
static void Log(object message, Object context);
static def Log(message as object, context as Object) as void
Parameters

message String or object to be converted to string representation for display.
context Object to which the message applies.
Description

Logs message to the Unity Console.

When you select the message in the console a connection to the context object will be drawn. This can be useful for locating the object on which an error occurs.

When the message is a string, rich text markup can be used to add emphasis. See the manual page about rich text for details of the different markup tags available.
// Message with a link to an object.
Debug.Log ("Hello", gameObject);

// Message using rich text. Debug.Log("<color=red>Fatal error:</color> AssetBundle not found");
using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Example() {
        Debug.Log("Hello", gameObject);
        Debug.Log("<color=red>Fatal error:</color> AssetBundle not found");
    }
}
import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Example() as void:
		Debug.Log('Hello', gameObject)
		Debug.Log('<color=red>Fatal error:</color> AssetBundle not found')