Burkinis have been in the news because they have been banned on some French beaches.
But what are they, why do people wear them, and why have they been banned?
Here's Newsround's guide to what's going on.
A burkini is a type of swimming costume that some Muslim women wear, which covers the arms, legs and hair.
To some Muslims, wearing clothes that cover these parts of the body is seen as a sign of modesty and of faith.
There are lots of different types of headscarves that Muslim women wear and some don't wear any.
A burkini is a version of these that can be used when swimming or on the beach.
It's called a burkini because it's a mix of the words 'burqa' - which is a type of Islamic clothing - and 'bikini'.
Some towns in France have banned women from wearing a burkini on public beaches or in the sea.
If they break the ban and wear one, they will have to pay a fine.
This is because in France religion is supposed to be completely separate from other parts of life in public.
This means that symbols of religion are banned in some public places.
Some politicians have now argued this should include the burkini.
Tensions have been high in France since a number of attacks by Islamist extremists and many people are arguing about the best way to respond as a country to what has happened.
Many people in France and in other countries think that it is not right to tell women what clothes they can and can't wear.
They say that it should be a choice whether to wear a burkini or not.
But others think that it is right for the burkini to be banned, as they say that it goes against the values and laws of France.
Some people also think that the burkini is a symbol of women's inequality to men in the Islamic religion.