Because you acquired the home by a gift, your basis usually is the basis that your parents had in the home (what they paid for it, plus capital improvements they made over the years). It may be difficult to reconstruct this information, but their initial cost may be available (e.g., published on Zillow).
An amount of gain on the sale of certain depreciable property that is treated as ordinary income in the case of personal property. Recapture is computed on Form 4797.