Numismatic in its definition is the study of coins, a numismatist is basically a coin collector. They may collect by series, type, mintmark, key dates in a series or whatever.
Coins are graded by condition. As condition goes up so does value. It's interesting to pick up a copy of A Guide to United States Coins, commonly known as the red book ok coin collecting, and yes the cover is cherry red.
In it you will see all your condition/wear factors of each type of coin and it's corresponding value, but only if you're buying, not selling, lol.
Don