is it long term preservation or long-term preservation
It should be **"long-term preservation"** with a hyphen. When "long term" is used as a compound adjective to modify a noun (like "preservation"), it should be hyphenated. This follows the general rule that compound adjectives are hyphenated when they appear before the noun they modify. Examples: - "long-term preservation" ✓ - "long-term storage" ✓ - "long-term effects" ✓ However, when "long term" functions as a noun phrase, no hyphen is needed: - "We're planning for the long term" ✓