When to use liner?

When to use liner depends on context, but generally use liner when you need extra layer for warmth, protection, moisture barrier, or to improve comfort and appearance. In clothing, use liner when coat or jacket needs warmth in cold weather, such as removable quilted liner in winter coat, or when you want smooth interior to make garment easier to wear over other clothes, or to hide seams for professional look. In makeup, use liner like eyeliner when you want to define eyes, and lip liner when you want to define lips and prevent lipstick bleeding. In bags, use liner when you want to protect interior and organize contents. In construction, use liner like pond liner when you need waterproof barrier to hold water. In waste management, use trash bag liner to line bin and keep it clean. In swimming pools, use pool liner to contain water. In general, use liner when you need inner protective layer that adds insulation, prevents leaks, protects outer material, or improves comfort and functionality.