Loom bands - they're the tiny colourful rubber bands that have become a massive craze around the world.
Boys and girls are spending hours weaving them into everything from bracelets to skipping ropes.
But some schools have started banning loom bands for various reasons, including playground fights, mess and them even being used as weapons.
The Duchess of Cambridge and Harry Styles are among the famous people spotted wearing loom band bracelets.
What do you think about loom bands?
We want to hear what you think about loom bands. Why are they so popular? What do you like to do with your loom bands?
Have loom bands been banned at your school?
Or perhaps you're not a fan and just don't get it?
Thanks so much to all of you who got in touch - we had loads of comments, and here's a selection of them below.
I think they should not ban them from school because they make people relaxed when they do them.
Sophie, Huntingdon, England
Loom bands are fun because you can make amazing designs: you can get more advanced and start making designs out of this world and there are sooooo many designs you can create.
Sofiya, Bury, England
Loom bands are a bad thing because they distract people from doing their work in my classes.
Mitchell, Long Eaton, England
I love loom bands as you can make them anywhere and they keep you entertained for ages.
Rebecca, Hertfordshire, England
I enjoy making loom bands because they're really easy and they don't take much time to do. Plus if you're bored, you can just take them apart and do them again.
Lolly, Wokingham, England
They're so easy to make, parents wear them, we can wear them, plus they're also for boys. Please do not ban them from my school.
Myles, Nottingham, England
I love making loom bands as they are easy and fun to make and wear. Also I have made a hair extension but we are not allowed to wear them in school.
Anisha, Stevenage, England
I think that loom bands are fun because you can make different patterns with the bands, they are a nice accessory and also you can experiment with different colours of bands and types of loom bracelets because there are many.
Jasmin, Barking, England
Loom bands are really fun to make. Lots of people have them in our school even though they're banned.
Lizzie, Dorchester, England
My school has banned them, despite there being no fights or mess. One class even sold loom bands to raise money for charity and they are not even allowed to wear those ones.
Alexandra, Cambridgeshire, England
It's fun because you can make anything you want. They've been banned in our school because people have been fiddling with them during classes. But when we put them away she still said no to them so they're banned for no reason now. Anyway, we make bracelets, necklaces, rings, skipping ropes and even earrings.
Charlie, West Sussex, England
I enjoy making loom bands, because they are entertaining and you can make really awesome looking bracelets, and it's so easy.
Ella, Birmingham, England
I think loom bands are amazing fun as they entertain you but our school has banned them because they are not part of school uniform, although all the teachers wear them.
Kyah, London, England
Loom bands bring everyone together at school. They help us be more creative and become friends with different people when we swap them.
Amber, Leicester, England
I thinks loom bands are epic because it's not just bracelets that you can make but other things as well, plus they're super cheap.
Sam, Derby, England
I love loom bands because they are such small and simple things and when there done they look really good, plus they're for boys and girls!
Annabelle, Clitheroe, England
My school has banned them! Its so unfair because we haven't had any fights or mess and no-ones made them in class. I've made absolutely loads and I can't wear them at school. I love loom bands.
Sophie, Salford, England
You get to show your creative side! If you wanted too, you could make anything! It's such a great idea to get children like me to use their imagination!
Cerys, Kent, England
Loom bands are epic! I love to make them for my friends, we all sit in the gazebo at break and make them in pairs! I also made a skipping rope!
Phoebe, Bristol, England
I love them because they are creative and you can do anything with them. Also you can trade ideas and tips with friends as well as trade the bands themselves! They are cheap things which you can spend your pocket money on.
Alanna, Pontypool, Wales
Loom bands are a great way to keep kids occupied for hours, making charms and bands, instead of spending loads of time on computers. They are fun and we sold them to raise money for charity.
Class 5B, Bristol, England
Loom bands are one of my favourite things to use. You can free your personality and also you can give them to friends.
Melissa, Saltcoats, Scotland
Every time I feel bored I take out my Rainbow Loom. You can also make money by selling bracelets and charms out of loom bands.
Aliya, Oxford, England
Loom bands give us something fun to do at break time. Everybody can create their own band, so they're inclusive too. Plus it allows you to be creative and make something that nobody else has ever before. They are not banned in our school and we particularly like the eighths. The most common type are known as fish tails.
Turtle Class, Pulham Market, England
We love making loom band bracelets for each other and our teacher. We spend hours at home making wonderful creations like fishtail bracelets, inverted fishtails, and even animals like an owl!
Year 2, Wigan, Greater Manchester
It is fun because you get to make cool designs and show them off to your friends! Plus it entertains people and can help take their minds off their troubles.