"Daddy, what are the white lines on the road made of?"

Very observant! The majority of the lines on the roads are made from hot thermoplastic which is a synthetic resin with colouring pigments and glass beads to make it reflective. It is heated in the tank of a special line marking machine. It melts into the surface and lasts for up to 10 years!
There's also a cold plastic paint which is mixed with a catalyst to make it harden. It is very durable but expensive. Solvent based paints are better for wet countries whilst water based paints are better in dry climates. Both take a bit longer to dry so we need to be careful not to step on the lines too soon! The easiest line marking comes in a roll and is cut to length and laid on the ground. It is heated and it melts onto the road. It is the most expensive so not much use if you have a lot of lines to paint!