Social networking is hugely popular. Many young people are confident and sophisticated in the way they use social media apps and websites.
However, social media, like all forms of public communication, comes with risks. Not all risks turn into problems but by helping your child understand what the risks are you can play a big part in preventing them turning into problems.
Please take the time to read the official UK Council for Child Internet Safety Guidance and talk to your children about it.
Further help keeping children safe on line can be found on the excellent Internet Matters website: https://www.internetmatters.org/
In particular, their guides for social media are very useful: https://www.internetmatters.org/advice/social-media-guides-parents/.