What is a key characteristic of labs in Google services?

Labs in Google services are experimental features that are not fully integrated into the main product. This means they are inherently unstable and can change or even cease to exist unexpectedly. Their experimental nature allows users to try out new ideas and functionalities that Google is testing, but it also means that these features may not be reliable or guaranteed to stick around.

While permanent features offer stability and support, labs are more about innovation and experimentation. They allow users to provide feedback on what works and what doesn't, helping Google refine and improve their services over time. This characteristic of being subject to change or removal is what distinguishes labs from the core features of Google services.