Screws are a good thing to use to screw things together.
A screw has a spirel around it so it makes it harder to pull out of what you screwed it in to.
You don't use a hammer to hammer in a screw you use a screwdriver to screw in a screw.
Screws are sharp and that's why we screw them into wood.
You should be careful with screws especially rusty ones because if they poke you they hurt and rusty ones will make you sick sometimes.
You can use screws for lots of different things.
Screws come in lots of different sizes.