They're big, round, available in all sorts of colours - and pretty heavy too!
Every time you go bowling, you probably spend a bit of time before the game agonising over which ball to use.
Those racks of multi-coloured orbs certainly offer a lot of choice. Which weight should I use? Which shade will best reflect my personality?
If you've ever wondered what bowling balls are actually made of and how they're created, we have the answer for you…
There are many different materials that go into a bowling ball, and each individual ball may have a combination of all or some of these depending on the manufacturer.
The main ingredients are plastic (or polyester), urethane, reactive resin and particle.
Plastic balls are very durable and inexpensive, making them the most common types of balls found in bowling alleys.
The materials used can have a huge bearing on things like durability, texture and the bowler's performance, which is why many serious bowlers opt to buy their own customised ball.
What's inside them?
You've probably learnt in geography class about the Earth's many layers, and the core right at its centre.
A bowling ball is very much the same - it has a couple of layers, including the coverstock, the outermost casing of the ball.
Inside the ball itself there is a core, which can be made in different shapes, sizes and materials to weigh the ball down sufficiently.
The core works to make up for some of the weight lost when drilling the holes in the ball, and its composition can affect a variety of factors such as its centre of gravity and trajectory down the lane.
Next time you head out for a game of bowling with your mates or for a corporate party, you'll be able to tell everyone exactly what makes the balls so heavy!