Paper money, like the U.S. dollar, is no longer backed by anything with real value - no gold, no silver, nothing that has value in and of itself. The "worth" of the dollar is continually eroded through inflation and dilution, making it worth less and less each day. Millions of people are coming to understand and act on the knowledge that holding physical silver is a way to protect and preserve what they have worked their whole lives for. Physical ownership of your silver is a must, because if you can't hold it, then you don't really own it.
The more people discover and decide to purchase physical silver, which is a finite precious metal, the less it is available for everyone else. There will come a time when physical silver, strictly because of supply and demand constraints, will not be readily available at a good price. Just as with a hurricane evacuation, when everyone rushes to the Interstate all at once, everything comes to a halt—demand for the asset is far greater than available supply. Only those with forethought who wisely headed for the Interstate before the mad rush were able to take full advantage of the asset. Physical silver will be no different.
Spot price is the current price at which pure silver can be purchased in the open market.