Bicycles/Maintenance and Repair/Chains/Chain clean and lube
Commonly dry and wet chain lubrification are utilized. A dry lube hardens on the chain and is excellent for dusty rides, but does not protect from moisture and is typically used in hot summer climates. A wet lube is used whenever there is a chance of water getting on the chain. The downside of a wet lube is that dirt readily clings to it causing wear of the bike's transmission components.
The proper method for lubricating a chain is to wipe off any dirt or old lube. Then drip fresh lube onto each link. Then turn the cranks backwards a few turns and wipe off any excess chain lube that has come to the surface (this old/excess lube will be black.)