YouTube Kids is an official Google app which creates a safer space for young children to explore videos online.
Smart algorithms and some human reviewing cut out the vast majority of unsuitable material (though there are no 100% guarantees), organising and presenting the rest in four main categories: Shows, Learning, Music and Explore.
A "Search" tool relies on algorithms alone, theoretically giving access to any other child-friendly content. There's also a greater chance of finding something unsuitable, but if you're unhappy then Search can be disabled and you'll still have access to the curated material.
The interface is simple and straightforward, big buttons giving quick access to only the essential options, so kids will be using it happily within a minute or two.
Useful settings give you control over what your children can do, and include a timer to place a limit on just how much they can watch.
Chromecast Plus! support means videos can now be viewed on your TV.
YouTube Kids looks good and is super-easy to use. Some users complain that they can still find unsuitable content, so you might want to monitor it for a while, but otherwise it's definitely worth a try.