How many of us know what websites our children are visiting and how safe they are? Most of the major Internet Service Providers (ISP) have the facility to set up parental controls. This is not usually set up by default, but requires an adult to log into their account online and setting this up. You may need to set up filters to allow some sites but not others as there may be some that children need to access for school work.
If your ISP doesn’t have an online parental control, many Internet Security packages, eg Kaspersky, Norton, McAfee etc have this capability. It requires an adult to set it up and create a password so that children can’t disable it or allow sites through. You may get pestered to allow some sites to be viewed but the inconvenience of allowing the occasional site by entering your password easily outweighs the chance of them viewing inappropriate websites.
However, you do it, protecting your children from inappropriate material is relatively straight forward and essential.