Most gardeners have leftover seeds after the season. Storing these seeds properly will make them last so they could be used in the subsequent seasons. 

Storing seeds is also important for those gardeners that collect their own seeds. 

When stored properly, some seeds can keep for more than 10 years or well beyond their sell-by date. Dampness and high temperatures is what can ruin seeds. So store seeds in a cool, dry, place out of direct sunlight. If you collect your own seeds make sure they are fully dry before storing. 

A great place to store seeds is the refrigerator. You will need to place the seeds in an air-tight, sealed container such as a jar or plastic bag. You can leave the seeds in their seed packets or put them in a labeled paper packet and place these in the sealed container. Put some silica gel packets or homemade packets of powdered milk, rice, or rice hulls to reduce humidity. Using this method, seeds could be successfully stored for a long time. 

Just make sure that when you remove seeds from cold storage, let the sealed container reach room temperature before opening to avoid condensation on the seeds.