The statement will advise if the works on the site can be used for educational purposes, within your organisation, under a Creative Commons licence or are free for use.
Concepts of 'Free' Meanings:
THINK ABOUT – Searching the Creative Commons website to find images from Flicker, Google images or Wikimedia commons, etc.
Using Creative Commons to find images on Google Image (0:30 min) by WhatcomElearning (YouTube)
The sites below host free, creative commons and licensed images for use.
The sites below contain images with no copyright restrictions and no requirement to attribute the source.