Heirloom varieties are older open-pollinated crop varieties — tomatoes, apples, peppers, beans — that predate modern hybrid plant breeding. They're typically grown from saved seed, offer distinctive colors and flavors, and prioritize taste over the shipping-and-shelf-life qualities that drive commercial variety selection.
Heirloom is closest in spirit to heritage-breed for livestock. At a farmers market, "heirloom tomatoes" means imperfect, varied, often less symmetrical fruit — but almost always better-tasting than the grocery-store standard.