diff --git a/README.md b/README.md
index 397aaea..00ec21d 100644
--- a/README.md
+++ b/README.md
@@ -3,4 +3,5 @@
 This repository is a playground for practising docker based programming following [docker-development-youtube-series](https://github.com/marcel-dempers/docker-development-youtube-series)
 
 * Topic 1: [Working with Dockerfiles (.NET, Golang, Python, NodeJS)](docs/working_with_dockerfiles.md)
-* Topic 2: [Working with code (.NET, Golang, Python, NodeJS)]
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+* Topic 2: [Working with code (.NET, Golang, Python, NodeJS)](docs/working_with_code.md)
+* Topic 3: [Multistage & Layers](docs/multistage_layers.md)
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diff --git a/c#/Dockerfile b/c#/Dockerfile
index b0dbb22..b1bdaeb 100644
--- a/c#/Dockerfile
+++ b/c#/Dockerfile
@@ -1 +1,21 @@
-FROM mcr.microsoft.com/dotnet/core/sdk:2.2
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+############# DEV IMAGE #################
+FROM mcr.microsoft.com/dotnet/core/sdk:2.2-stretch as dev
+
+RUN mkdir /app/
+WORKDIR /app/
+
+COPY ./src/work.csproj /app/work.csproj
+RUN dotnet restore
+
+COPY ./src/ /app/
+RUN mkdir /out/
+RUN dotnet publish --no-restore --output /out/ --configuration Release
+
+############## PRODUCT IMAGE #############
+FROM mcr.microsoft.com/dotnet/core/sdk:2.2-stretch-slim as prod
+
+RUN mkdir /app/
+WORKDIR /app/
+COPY --from=dev /out/ /app/
+RUN chmod +x /app/
+CMD dotnet work.dll
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diff --git a/docker-compose.yaml b/docker-compose.yaml
index eef3c82..4cebf45 100644
--- a/docker-compose.yaml
+++ b/docker-compose.yaml
@@ -4,7 +4,8 @@ services:
     container_name: csharp # image name
     image: cruxlight/csharp_sdk:1.0.0
     build:
-        context: ./c#
+      context: ./c#
+      target: dev
     working_dir: /work
     entrypoint: /bin/sh
     stdin_open: true
@@ -16,7 +17,9 @@ services:
   golang:
     container_name: golang
     image: cruxlight/golang_sdk:1.0.0
-    build: ./golang
+    build: 
+      context: ./golang
+      target: dev
     working_dir: /work
     entrypoint: /bin/sh
     stdin_open: true
@@ -28,7 +31,9 @@ services:
   nodejs:
     container_name: nodejs
     image: cruxlight/nodejs:1.0.0
-    build: ./nodejs
+    build: 
+      context: ./nodejs
+      target: dev
     working_dir: /work
     entrypoint: /bin/sh
     stdin_open: true
diff --git a/docs/multistage_layers.md b/docs/multistage_layers.md
new file mode 100644
index 0000000..43ca631
--- /dev/null
+++ b/docs/multistage_layers.md
@@ -0,0 +1,88 @@
+# Multistage & Layers
+
+Previously, in [Topic 2, Working with Code](working_with_code.md), we have dockerfile to create isolated DEV environment, but we still have to manually `dotnet new/build/run`
+
+Target: Use multistage dockerfile to automatically setup DEV & PROD environment, where we only need to modify source code.
+
+## What is Docker Image Layering?
+
+dockerfile lay layers on top of another. So often changed layers should be in bottom to save image building time
+
+### General DEV + PROD multistage dockerfile structure
+
+```dockerfile
+######## Dev stage #########
+# Start from a base image (Layer 1)
+FROM base-SDK-image-here 
+
+# install dependencies (Layer 2)
+RUN pip install \npm install \go get
+
+# Copy source code into image (Layer 3)
+COPY source
+
+# Run assembly to build app based on source code (Layer 4)
+RUN build
+```
+
+Above is the dockerfile for a development environment. To product ready, we can use multistage. By giving above codes an alias, we can build multi-stage images
+
+continue dockerfile
+
+```dockerfile
+####### Runtime stage #########
+# Using a runtime image instead of full SDK (Layer 5)
+FROM another-image 
+
+# Copy compiled app into runtime image to save space (Layer 6)
+COPY output-from-stage-1
+
+# Start app or entrypoint
+RUN application 
+```
+
+Benefit of this multistage, we can use debug tools in dev stage, but also keep product small in stage 2
+
+## Modify dockerfile and docker-compose for multistage building
+
+### Add build target in docker-compose
+
+Adding build target in `build`, so docker-compose can be directly used to create DEV/PROD image.
+
+```docker-compose
+    build:
+      context: ./c#
+      target: dev
+```
+
+### Modify dockerfile
+
+```dockerfile
+############# DEV IMAGE #################
+# Define a dev stage using `as`
+FROM mcr.microsoft.com/dotnet/core/sdk:2.2-stretch as dev
+
+# Defining a working directory
+RUN mkdir /app/
+WORKDIR /app/
+
+# ????
+COPY ./src/work.csproj /app/work.csproj
+RUN dotnet restore
+
+# Copy the remaining source file
+COPY ./src/ /app/
+RUN mkdir /out/
+RUN dotnet publish --no-restore --output /out/ --configuration Release
+
+############## PRODUCT IMAGE #############
+FROM mcr.microsoft.com/dotnet/core/sdk:2.2-stretch-slim as prod
+
+RUN mkdir /app/
+WORKDIR /app/
+
+# Copy binary into folder
+COPY --from=dev /out/ /app/
+RUN chmod +x /app/
+CMD dotnet work.dll
+```
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diff --git a/golang/Dockerfile b/golang/Dockerfile
index 9bd917b..0e03708 100644
--- a/golang/Dockerfile
+++ b/golang/Dockerfile
@@ -1 +1,18 @@
-FROM golang:1.12.5-alpine3.9 as builder
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+################ DEV IMAGE ################
+FROM golang:1.12.5-alpine3.9 as dev
+
+RUN apk update && apk upgrade && \
+    apk add --no-cache git
+
+RUN go get github.com/sirupsen/logrus
+RUN go get github.com/buaazp/fasthttprouter
+RUN go get github.com/valyala/fasthttp
+
+WORKDIR /work
+COPY ./src /work/
+RUN go build -o app
+
+################## PROD IMAGE #################
+FROM alpine:3.9 as prod
+COPY --from=dev /work/app /
+CMD ./app
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diff --git a/nodejs/Dockerfile b/nodejs/Dockerfile
index 56d9a22..f90ba3e 100644
--- a/nodejs/Dockerfile
+++ b/nodejs/Dockerfile
@@ -1 +1,16 @@
-FROM node:12.4.0-alpine
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+########### DEV IMAGE ##########
+FROM node:12.4.0-alpine as dev
+
+RUN mkdir /app/
+WORKDIR /app/
+
+# package.json is the only one will be changed when new dependency added
+COPY ./src/package.json /app/package.json
+RUN npm install
+
+COPY ./src/ /app/
+
+############ PROD IMAGE ##############
+FROM dev as prod
+
+CMD node .
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diff --git a/python/Dockerfile b/python/Dockerfile
index caac651..7a285f7 100644
--- a/python/Dockerfile
+++ b/python/Dockerfile
@@ -1 +1,20 @@
-FROM python:3.7.3-alpine3.9
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+FROM python:3.7.3-alpine3.9 as dev
+
+RUN mkdir /app/
+WORKDIR /app/
+
+COPY ./src/requirements.txt /app/requirements.txt
+RUN pip install -r requirements.txt
+COPY ./src/ /app/
+
+############# PROD IMAGE ##############
+
+FROM python:3.7.3-alphine3.9 as prod
+
+RUN mkdir /app/
+WORKDIR /app/
+
+COPY --from=dev /app/ /app/
+RUN pip install -r requirements.txt
+ENV FLASK_APP=server.py
+CMD flask run -h 0.0.0 -p 5000
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