Here are some commonly used instructions in a Dockerfile:

1. 1. FROM: Specifies the base image for your Docker image. It is typically the starting point for your Dockerfile. For example, `FROM php:7.4-fpm` selects the PHP 7.4 image with FPM (FastCGI Process Manager).
2. 2. WORKDIR: Sets the working directory inside the container where subsequent instructions will be executed. It is recommended to use an absolute path. For example,` WORKDIR /var/www/html` sets the working directory to ` /var/www/html`.
3. 3. ADD instruction copies new files, directories or remote file URLs from and adds them to the filesystem of the image at the path < dest >. ADD has two forms:

   
   ADD [--chown=< user >:< group >] ["< src >",... "< dest >"] 

   (this form is required for paths containing whitespace)

   
   ADD [--chown=< user >:< group >] < src >... < dest >
   

5. 4. COPY: Copies files from the host machine to the container. It takes two arguments: the source path on the host machine and the destination path inside the container. For example, ` COPY . /var/www/html` copies all files from the current directory on the host to the ` /var/www/html` directory inside the container.
6. 5. RUN: Executes commands inside the container at build time. It can be used to install packages, run scripts, or perform any necessary setup. For example,

   RUN apt-get update && apt-get install -y curl

   updates the package lists and installs the` curl` package inside the container.
8. 6. ENV: Sets environment variables inside the container. These variables can be accessed during the build process or when the container is running. For example, ` ENV APP_ENV production` sets the ` APP_ENV` environment variable to` production`.
9. 7. EXPOSE: Informs Docker that the container will listen on the specified network ports at runtime. It does not actually publish the ports. For example, ` EXPOSE 8000` indicates that the container will listen on port 8000.
10. 8. CMD: Specifies the command to run when the container starts. It is usually the main process of the container. There can only be one CMD instruction in a Dockerfile. For example,

    CMD ["php", "artisan", "serve", "--host=0.0.0.0", "--port=8000"]

    runs the Laravel development server when the container starts.