Link
Also known as: Hyperlink
A link is a door. You press it and you are somewhere else.
In a house, a door connects two rooms. You walk through it and now you are in the kitchen.
On the internet, a link is the door. You press the blue words and you are in a different place. Sometimes it is a different page of the same website, like walking to the next room. Sometimes it is a completely different website, like walking out the front door to the house next door.
Doors are how people get around. A place with no doors is a place nobody can reach.
Color this: draw two houses and one road between them. That road is a link.
For the grown-up holding the crayon box:
Links do two jobs at once: they move people, and they pass a signal about what is worth visiting. The second job is invisible to the reader and is most of what made search work in the first place.