Should there be an agerestriction  on social media

The Internet is really usefull, but it has some really bad sides like cybermobbing, aggresive Videos and pornography. Children watching some of these things dont understand the consequences it can bring. Older People are more mature and know the consequences. But still I dont like the idea of having an age restriction of 18 years on the Internet. It can help to contact people, it can help for learning in school and a lot of other things. I think there should not be an age restriction on the Internet, but there are programs that can avoid children to go to specific pages. Those programs should be used more.