- you can find the complete code here -> https://github.com/udacity/course-ud303
- you write web servers from scratch and know how each component holds together 
- Hello server (just prints hello when a request is hit)
- Echo server (little dynamic, prints whatever you pass as query param)
- MessageBoard server (POST requests, shows all previous messages)
- BookMark Server(urlShortner, stores all urls with shortnames)
- JSON
# Key Points to learn:
  - Headers are important and they vary with kind of requests.
  - You can send html forms as string to display in browser via a request
  - Content-type is set according to what you are gonna send to browser, and getting it wrong throws a TypeError
  - Write good error messages and print statements to understand the flow.
 # Deploying to heroku
 1. create an account on heroku and install heroku cli
 2. put project in a new git folder
 3. create 3 config files:
    #1. runtime.txt tells Heroku what version of Python you want to run.
    #2. requirements.txt is used by Heroku (through pip) to install dependencies of your application that aren't in the Python standard library.
    #3.Procfile is used by Heroku to specify the command line for running your application.
    NOTE: to create a Procfile in windows: echo web: run this thing >Procfile (and later edit it)
 4. configure port to listen from environment variables
 5. heroku create app-name //to create app
 6. git push heroku master ...and voila! You have the url of deployed server