Lingual braces sit on the inside surface of your teeth. They're often called hidden braces because their positioning means you can't see them from the outside.
Lingual braces are attached to your teeth much like fixed braces are. The brackets of the brace will be attached to the inner surface of your teeth, connected by a wire. They're a great option if you're looking for a treatment that'll straighten your teeth, but a little more discreetly than traditional braces.
If you want to straighten your teeth, but are concerned about the look of braces, lingual braces offer a much more subtle alternative. They're also a great option if you're into activities such as contact sports or play a wind instrument, as they can offer much less disruption to these hobbies than traditional fixed braces. What's more, lingual braces are suitable for all ages.