Especially favored in the US housing market from the 1990s onward, open-plan layouts remove the wall between kitchen and living room so whoever's cooking can still talk to family or guests, or watch TV with them. The space also reads larger than its actual square footage, and light spreads without a wall in the way.
Zoning fills in for the missing walls. Different flooring in just the kitchen, an island counter with its back toward the living room, or a rug's edge marking where the living zone starts — all substitute for a wall. Lighting often differs by zone too — downlights in the kitchen, floor lamps in the living room — to visually separate them.
The tradeoff is that cooking smells and noise now travel straight into the living room, and fewer walls means less wall space for storage or mounting a TV. Planning stronger ventilation, and using an island or a partial wall for minimal storage, are common ways to compensate.
When to use
Use it to make a small home feel larger, or to stay part of the conversation while cooking. Plan strong ventilation without fail, and use zoning to make up for the walls that are gone.