diff --git a/Dockerfile b/Dockerfile
index 159250f..0bb0abb 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -3,25 +3,33 @@ FROM debian:buster
 RUN apt update
 RUN apt install -y make debootstrap supervisor isc-dhcp-server tftpd-hpa busybox squashfs-tools
 
-# Linux image
+# Builds Linux for cloning image. The Makefile in linux/ would download base
+# debian system to linux/build/cache itself, but to speed up rebuilding this
+# Docker container the download is run separately to avoid repeating it in
+# future builds.
 ADD linux /linux
 RUN mkdir -p linux/build && debootstrap buster linux/build/cache
 RUN cd /linux && make
 
-# Files to be served
+# Creates and populates /tftpboot directory. Files stored there will be served
+# by TFTP and HTTP (on port 8014).
 ADD src/tftpboot /tftpboot
 RUN cp /linux/build/rootfs/initrd.img /tftpboot/initrd.img && \
 	cp /linux/build/rootfs/vmlinuz /tftpboot/vmlinuz && \
 	mksquashfs /linux/build/rootfs /tftpboot/root.squashfs
 
-# Supervisor
+# Supervisor's config
 COPY src/supervisor.conf /supervisor.conf
 
-# DHCP server
+# DHCP server config
 RUN mkdir -p /var/lib/dhcp && touch /var/lib/dhcp/dhcpd.leases
 COPY src/dhcpd.conf /etc/dhcp/dhcpd.conf
 
+# The run.sh script setups networking and starts supervisor.
 COPY src/run.sh /run.sh
 RUN chmod +x /run.sh
+
+# Interface on which the server will be listening. Set with `-e INTERFACE=eth1`
 ENV INTERFACE=eth0
+
 CMD ["/run.sh"]