Kibble is dry pet food produced by extrusion: ingredients are ground, mixed with water, cooked under pressure, then forced through a die that shapes the pellets. Extrusion is fast and cheap but high heat can degrade some heat-sensitive nutrients, which are typically replaced via post-cook supplementation. Kibble is shelf-stable, cheap per calorie, and convenient. The trade-offs are lower moisture content (a concern especially for cats) and inherently higher carbohydrate content vs wet food.