Preservation techniques are methods used to maintain the quality and longevity of various items, such as food, documents, and artifacts. Common techniques include refrigeration, canning, and drying for food, while archival methods like acid-free storage and climate control are used for documents and historical items. These techniques help prevent spoilage, decay, and damage, ensuring that valuable items can be enjoyed or studied for years to come. For example, canning allows fruits and vegetables to be stored safely for long periods, while archival storage protects important historical documents from environmental harm.