Coins that are smooth to the touch are often referred to as "uncirculated" coins. These coins are typically newer and have not yet been put into circulation. Uncirculated coins are often purchased by coin collectors and are considered to be more valuable than circulated coins.
Ridged Coins
Coins with ridges, or "reeding," are often referred to as "circulated" coins. These coins have been put into circulation and have been handled by many people. Circulation causes coins to become worn and dirty, and the ridges help to protect the coin's design from being worn away. Ridged coins are typically less valuable than uncirculated coins.