You find a nice picture on the internet that you want to use on your website. Can you do this? Unfortunately no. Copyright gives only the creator – in this case the photographer – the exclusive right to communicate to the public, publish and reproduce their work, provided the work is original. Creators can also set conditions under which others may use their work, for example with a licence such as the Creative Commons licence, which means that the work can be freely used under the circumstances stated in the licence. Copyright can also be transferred. So it’s possible you don’t only have to contact the original author, but also the right holder to whom the rights are transferred. This might be a collective management organisation like Pictoright (NL), Sofam (BE) ... for photographs or Buma/Stemra (NL), SABAM (BE) ... for music.
If you use a copyright-protected work without the creator’s permission, you will be committing a copyright infringement which can lead to court proceedings. Therefore, if you want to use a creative work from someone else, check whether it is protected by copyright and what the conditions are.