Cable ties are like tiny little straps that can hold things together. Think of them like the little plastic snap bracelets you might have had as a kid, but instead of going on your wrist, they go around things like cords and wires.
You can make them tight by pulling on the end that sticks out, and once they're tightened, they stay that way until you cut them with scissors or another tool.
People use cable ties to organize messy cords behind their electronics, secure things to bike racks or roof racks on their cars, and even to make creative art and crafts! They're super useful and come in all different sizes, colors, and strengths.