What is the best way to store left-over flower and vegetable seeds?

FAQ
Question: 

What is the best way to store left-over flower and vegetable seeds?

Answer: 

If stored properly, the seeds of many vegetables and flowers will remain viable (alive) for 2 to 3 years.  Ideal storage conditions are cool and dry.  It’s generally best to keep the seeds in their original packets.  Fold over the ends of opened seed packets, then place the surplus seeds in a tightly sealed jar or plastic lidded coffee can.  Place 1 to 2 tablespoons of powdered milk in a small envelope and place the envelope in the container.  The powdered milk will absorb the moisture from the air inside the container and keep the seeds dry.  Place the tightly sealed container in the refrigerator or other cool location.