Direct answer
Many smart switches require a neutral conductor because their electronics need continuous power even when the light is off. Some controls are specifically designed to operate without a neutral, but they may have minimum-load requirements or different LED compatibility. Lutron explains why neutral-based controls can improve continuous power and load performance in its technical guidance.
Do not identify wiring only from insulation color or a photograph. Older homes, remodeled circuits, multi-location controls, and crowded boxes can have unexpected conditions. A qualified electrician should verify conductors, grounding, box depth, load type, and circuit condition. If no neutral is available, options can include an approved no-neutral control, adding a neutral, relocating the device, or using a compatible centralized solution.
Sources and technical references
Use the organizations responsible for a product, platform or standard to confirm current specifications and compatibility.
How this answer was prepared
Camelback Smart Homes publishes this FAQ library for homeowners, design professionals, builders and property teams comparing integrated technology. Answers begin with the practical conclusion, then explain the factors that can change it.
Limitations: This is general educational information, not a site-specific design, quote, code determination or compatibility guarantee. Final requirements depend on the property, construction, infrastructure, equipment versions and project goals.