Rzipper commented on Simple Private App

Also looking for a "Hello World" app example in any programming language.

The language used around applications in Shopify is very confusing for someone new to the environment. 

"Private Apps:

As a Shopify developer, you have the option of creating public or private apps. Public and private apps share the same functionality except for the fact that private apps are locked to one shop. This means that only one shop will ever have access to a private app."

This is not really true is it? If I generate a private app API key on my own store, I can't add proxy urls, I can't call in content from an outside script to use in my store, etc. 

It seems like in Shopify sometimes the term Private app is used for an application you create under a partner store for use in a separate single store (basically a Public App that hasn't been published in the marketplace).

I someone could explain the differences between a Private App created within your store and an App you create for your own store with a developer account that would be helpful.

Here's the scenario for which I am looking for a HELLO WORLD example:

I created an App in my developer account and installed it with permissions:

https://SHOP_NAME.myshopify.com/admin/oauth/authorize?client_id=APP_API_KEY&scope=write_products,write_content,write_customers,write_orders

I set up a proxy url to go to a script that returns "HELLO WORLD", but when I go to the proxy url I get a Server 500 error instead of "HELLO WORLD". DO I need to return "HELLO WORLD" in some format other than a normal html document?

Also, if I wanted to include content from my app within a liquid page how would I go about this?

Thanks!

R