Can you explain the concept of layers in Docker and their role in containerization?

In Docker, layers are separate changes to the filesystem that are stacked on top of each other, forming the final container image.

Each layer is created when a command is executed in the Dockerfile (for example, copying files, installing packages) and is stored separately. When a container is run, Docker combines all layers into a single entity.

The role of layers:

• Storage efficiency: shared layers between images are stored once, saving space.
• Caching: during image building, Docker reuses unchanged layers, speeding up the process.
• Change isolation: each layer records a specific change, simplifying management and updating of images.

Thus, layers enable the creation of lightweight, quickly assembled, and updatable images, which is a key advantage of containerization.