The previous answerer gave you a excerpt from Wikepedia. Here is another that might help:
Very little is known about the size of the universe. It may be trillions of light years across, or even infinite in size. A 2003 paper  claims to establish a lower bound of 24 gigaparsecs (78 billion light years) on the size of the universe, but there is no reason to believe that this bound is anywhere near tight. See Shape of the Universe for more information.
The observable (or visible) universe, consisting of all locations that could have affected us since the Big Bang given the finite speed of light, is certainly finite. The comoving distance to the edge of the visible universe is about 46.5 billion light years in all directions from the earth; thus the visible universe may be thought of as a perfect sphere with the earth at its center and a diameter of about 93 billion light years. Note that many sources, including previous versions of this Wikipedia article, have reported a wide variety of incorrect figures for the size of the visible universe, ranging from 13.7 to 180 billion light years.