Enjoy the beer that you deserve.
What it does :
Bottle caps help you keep your filled bottles closed until your beer is ready to be consumed.
What it is:
A bottle cap is simply a metal disk with a crimped rim and a plastic seal attached to one side.
How it works:
A bottle capper folds the crimped rim of a cap down around the bottle lip. Combined with the plastic seal under the cap, the bottle contents are sealed to the outside air. You should ensure that the caps are securely placed, or a bottle-fermented brew can 'pop its top'. Also, poorly capped beer can also oxidize and result in a papery taste. In either case the result is a wasted brewing effort.
Bottle caps are used during the cold side of brewing (e.g. fermentation, bottling, and packaging). The caps come in direct contact with the beer during the bottle conditioning stage. So, the caps should be sanitized before use to prevent contamination.