An ideal soil texture combining sand, silt, and clay in balanced proportions, creating good drainage, water retention, and workability—the "Goldilocks" of soil types.
Loam is the sweet spot: not too sandy (doesn't hold water), not too clayey (doesn't drain), but balanced. It has good pore space (drains well, roots penetrate easily), holds adequate moisture and nutrients, and is easy to work. Most plants thrive in loam. Improving sand and clay toward loam is the goal of soil amendment.
Loam is what you're trying to create by amending poor soils. Knowing loam characteristics helps you understand what you're working toward.