They generally look like translucent specks of
various shapes and sizes or like cobwebs. They are frequently seen when you
look at a plain lighted background like a blank pastel wall, a blue sky, or the
white pages of a book.

There are a number of
possible causes of floaters. They may be small flecks of protein or matter
that were trapped during the formation of your eyes before birth and remain
suspended in the clear fluid. More commonly, they occur as we age: the vitreous thickens
and clumps, floaters result from the clumped vitreous gel, and can also form
from dead cells that are shed as new cells are created.  

Sometimes flashes or
streaks of light may appear. This may be happening because the jelly-like
vitreous is shrinking and pulling on the retina. This can indicate a serious
condition such as a retinal detachment. The retina can tear when the shrinking
vitreous pulls away from the wall of the eye.

Floaters by themselves
are usually harmless, but when accompanied by flashes or steaks of light
can be symptoms of a retinal detachment and should be quickly seen by your
optometrist.