FROM: This specifies the base image that the build will extend.

WORKDIR: This instruction specifies the "working directory" or the path in the image where files will be copied and commands will be executed.

COPY: This instruction tells the builder to copy files from the host and put them into the container image.

RUN: This instruction tells the builder to run the specified command.

ENV: This instruction sets an environment variable that a running container will use.

EXPOSE: This instruction sets configuration on the image that indicates a port the image would like to expose.

USER: This instruction sets the default user for all subsequent instructions.

CMD: This instruction sets the default command a container using this image will run.

ENTRYPOINT: This instruction configures a container to run as an executable.

To read through all of the instructions or go into greater detail, check out the Dockerfile reference.