What is the role of layers in Docker container architecture and why are they used?

In Docker, each image consists of multiple layers. Each layer represents changes compared to the previous layer, such as installing a package or copying files. Layers are used for:

• Efficient storage: layers are cached and can be reused by different images, saving space.
• Fast building: when the Dockerfile is changed, only the modified layers are rebuilt.
• Version control: it is possible to see what changes were made at each layer.

For example, if you have a base layer with the OS, then a layer with Python installed, and a layer with your application, then when the application changes, only the last layer is rebuilt, while the base layers remain unchanged.