The subject has been discussed many times here and is still difficult to conceive. A basic tenet though, is to use the term "observable universe" when discussing your question. If limited to that term(the definition is to lengthy to present here) alone, then we find the latest theory suggests the "universe" is exapanding and is expanding at an accelerating pace. Having said that, it does not have an "edge"... it is not expanding "into" something. Simply put, there is nothing for it to expand into since the universe carries with it its own definition of space. The old, worn, adage of an inflating balloon is still, probably, the easiest analogy to understand. The Big Bang is likened to a balloon in that, shortly after the intial creation (10-^44 seconds) the substance of creation began an expansion with all the potential pieces and parts we observe today being carried out in all directions like the balloon. An insect scrambling along on the surface of this balloon never gets "off" the balloon and if the insect were able to travel for a near infinity of time, would return to its place of beginning. Very "freaky" indeed. In fact the very latest experiments indicate the earliest moments of the creation event are now found to have behaved like a fluid, rather than a gas as previously thought...