What are floaters?
Floaters are the effect of particles moving across the eye caused by small clusters of cells breaking off the inside wall of the eye and floating in the gel that fills the eye.
Unless there are many of them or they're accompanied by other visual phenomena such as lights or a 'curtain' across the vision, they're unlikely to be harmful.
It's always worth mentioning them next time you visit your optician.
If they're numerous and accompanied by other visual symptoms, get them checked out urgently by your optician.